An exciting talent, Diouf had an outstanding World Cup for Senegal and helped his side reach the quarter-finals before they lost 1-0 to Turkey.
Diouf first came to the public eye with his stunning performance in the opening World Cup win over France. He created the only goal of the game and led defenders Lebouef and Desailly a merry dance.
His move from northern France was no shock, since Marseille, Tottenham, Aston Villa, Chelsea, Inter Milan, AC Milan and Parma had all considered prising him away.
But while others waited, Houllier moved in, signing the current African Footballer of the Year on a five-year deal before that clash with France.
Diouf kicked-off his French career at Sochaux, playing 15 league matches in 1998/99. But it wasn't until the following season, with Rennes, that he scored his first goal.
Diouf's move to Liverpool represents the latest landmark in the career of a player who is on course to become Africa's biggest name since George Weah.
Diouf, twice named African Player of the Year, arrived at Liverpool after the 2002 World Cup as one of the best players in the world, named in FIFA's team of the tournament and a big buy at around £10million.
When he finally left Anfield for good three years later he had built up a reputation as a disruptive influence, an expensive mistake and - as far as the Reds were concerned - a misfit.
His escape route came via Bolton Wanderers, where he had spent the 2004/05 season on loan after new boss Rafael Benitez had spent little time jettisoning him from his squad.
Bolton boss Sam Allardyce had again proved his skill at moulding the games rough diamonds and wayward stars into effective performers for his side. But despite his star quality on the pitch he continued to court controversy off it.
His antics almost persuaded Allardyce to ditch plans for a permanent transfer. In the end Diouf let his feet do the talking on the pitch, helping the Trotters into the Europe, namely the UEFA Cup, for the first time in their history.
Liverpool snapped up the Senegal star from Lens for £10million fee a few weeks after he had helped his country to a superb 1-0 victory over France in the opening game of the World Cup in Korea/Japan.
Senegal qualified for the finals largely thanks to two qualifying hat-tricks netted by Diouf, and would go on to make the last eight.
The forward, who moved to Lens via Dakar, Sochaux and Rennes, is a strong running player who earned the nickname 'Serial Killer' from his team-mates due to his impressive goalscoring tally.
Disciplinary problems dogged the early stages of Diouf's career at Rennes - a trait he has struggled to shrug off in England.
Diouf signed a five-year deal at Anfield. He made his bow in the 1-0 FA Community Shield defeat at the hands of Arsenal.
And he was immediately welcomed into the hearts of the Anfield fans as he scored twice on his home debut in a 3-0 win against Southampton.
But after that he struggled badly to find his form - and failed to score again in the League until March.
That joy was short-lived, as just five days later he spat at a Celtic fan after falling into the crowd during a UEFA Cup tie at Parkhead. The player was immediately substituted by manager Gerard Houllier and left out of the squad for the return leg.
But worse was to follow. He was banned for two games by UEFA, and then charged with assault - to which he pleaded not guilty. He eventually admitted to assault under provocation in September 2003 in court in Glasgow and was fined £5,000.
Diouf scored just six goals in the 2002/03 season, and only three in the Premiership, but towards the end of the season began to excel in midfield.
And in the early weeks of the 2003/04 season, there were signs that he could become a real success when playing on either flank.
But the player never managed to find any sort of form or consistency at Anfield, and when Houllier left at the end of the 2003/04 campaign it was clear he had little future on Merseyside.
Back on the international stage, in February 2004 he was banned for three international matches after being found guilty of violent conduct in an African Nations Cup quarter-final with Tunisia. He appealed the decision and was given a fourth match to sit out for his troubles.
When the squad list was announced for the 2004/05 season, Diouf found himself without a number and left out of the club's tour to the USA.
Diouf moved on in August 2004, joining Bolton on a season-long loan deal. The player rejected a switch to Serie A side Fiorentina.
It started so well for the player at the Reebok. He soon became a cult figure among the supporters, playing in a deeper role in support of what was normally a loan striker in Allardyce's side.
In October his Senegal troubles resurfaced when he was banned from playing for his country for at least six months after being kicked out of the squad ahead of a World Cup qualifier in Liberia.
The suspension came after Diouf had spent much an evening in a Dakar night club.
His reputation as a pathological expectorator struck again in November when he was shown on TV to spit directly into the face of Portsmouth's Arjan de Zeeuw. He was lucky to escape with no more than a three-match ban.
To add to that, he would eventually be charged by police with disorderly conduct over allegations of spitting his drink at Middlesbrough fans after being substituted at the Riverside Stadium earlier in November.
Diouf was then sent off after just eight minutes of an FA Cup tie against Arsenal in March for stupidly elbowing goalkeeper Jens Lehmann off the ball.
It led to Allardyce questioning the merits of signing a player with so much baggage on a permanent basis.
However, Diouf had shown his worth when coming back from the first ban. Bolton had struggled without him and shortly after his return they won seven consecutive matches.
His nine Premiership goals, from a deep-lying position, were vital to the club's European qualification.
Bolton did complete the signing of Diouf in June 2005, for an undisclosed fee on a four-year contract.
Liverpool certainly would have got nowhere near the £10million they shelled out on one of the games most promising stars three years earlier. In two years at Anfield, Diouf scored just six goals in 80 appearances.
'It is wonderful news that I will be joining Bolton,' he told the club's website. 'Sam Allardyce is the best manager I've ever worked with. He makes you feel important and most of all lets you play football without worrying about anything else.'
Allardyce was similarly delighted with the signing, saying: 'He has all the skills in the world to become one of our most significant signings in the modern era of this great club.'
DIOUF SPEAKS TO LIVERPOOLFC.TV
Anfield's man-of-the-moment - the in-form El Hadji Diouf - gives a rare interview to Liverpoolfc.tv at the club's Melwood training headquarters...
Liverpoolfc.tv: El Hadji, you've started the season in great form, you must be pleased at how things are going?
Diouf: Yes. When I first joined I had the choice of a lot of other big clubs but I chose Liverpool because I liked the coaching staff here and I believed it is a club that is going places. I still do and I'm very happy here.
Gerard Houllier says your best is yet to come. Do you agree?
I want to progress and I am progressing at a great club. My aim is to continue to get better and better.
Would you admit that your first season here was a disappointment?
The season before I joined Liverpool I played over 70 games and done a lot of travelling. With Lens we progressed in the cup and I was at the World Cup with Senegal. So when I got here I was very tired. Last season was a difficult one for everybody at the club, myself included. But this season is going to be a lot better.
What is your preferred position - out wide or up front?
I just like to play and I'm happy playing wherever the boss want me to.
Are you confident Liverpool can challenge for the major honours this season?
Because of the group of players we have here I am sure we will be competing for prizes come the end of the season.
What do you like most about playing in English football and how does it compare to France?
I like the fact that the stadiums are always full. Also the games are hard and competitive. Since playing in this country I have forgotten all about playing in France, although I do still watch it on television. Technically it is very good but as I've said I like the competitiveness of the English league.
How have you found living in the city of Liverpool?
I'm very happy living here and happy that I didn't move to London, Marseille or Paris. Liverpool is bigger than Lens, where I previously lived, but I'm enjoying it very much.
Was it difficult to settle when you first arrived?
As soon as I arrived here we went to a training camp in Switzerland and that helped me get to know all the players. It was a very good introduction to life at this club and I found things a lot easier after that.
Who are you best friends at the club?
I am friendly with all the players. Everybody expects me to be good friends with Salif (Diao) with us both being from Senegal but I wouldn't say we are close friends who stick together all the time. I like to think I'm an outgoing person and this helps me get on with all the other players.
You always seem to have a smile on your face...
It's not always sunny here so I have to light up the place with a smile!
Going back to your childhood in Senegal, did you know of Liverpool Football Club?
All the great clubs - Liverpool, Real Madrid and Inter Milan - were spoken about in the same sentence, so yes Liverpool Football Club was very famous even when I was young.
Did you have a favourite football club who you followed?
I liked Robbie Fowler and that made me like Liverpool. Robbie was young at the time and scored so many goals, that is why I liked him and why I chose to support Liverpool. John Barnes also, we used to hear all the news about him.
What inspired you to become a professional footballer?
At first I was going to join the police force but my family advised me to concentrate on football as it was a better career. And, of course, the money is better! African people support their families a lot and what ever was better for my family was better for me.
Can you tell us a bit about your interests outside of football?
I recently became a father so I spend a lot of time with my baby. I also like to watch American sports on television and sleep. I sleep a lot! Another interest would be shopping and I do this quite a lot with Emile (Heskey). There is a lot of competition between some of the players in the fashion stakes. We try to outdo each other by seeing who can wear the most outrageous clothes and at the moment I am numero uno!
Already in your career you've played in the World Cup and twice been named African Footballer of the Year, but what is your ultimate ambition in the game?
I like to win things and I've made my imprint in Africa by winning lots of awards there such as the Golden Ball. Now I want to win medals here. I have no specific aims but the Premiership and Champions League would be nice.
And how is your English coming on?
I'm picking it up slowly but when the Scousers talk I can't understand a word they say. They speak to fast!
Do you know any Scouse words?
I know a lot of Scouse words. Emile has taught me all the bad ones!
