Birthdate: 10 February 1977
Birthplace: Kédougou, Senegal
Other clubs: Monaco (1996-2000), Epinal (loan 1996), Sedan (2000-02), Birmingham City (loan 2005), Portsmouth (loan 2005-06), Stoke City (loan 2006-07 + transfer 2007-12)
Bought from: Sedan
Signed for LFC: £4.7m, 06.08.2002
International caps: 39/4 (2009)
Liverpool debut: 28.08.2002
Last appearance: 03.01.2005
Debut goal: 02.10.2002
Last goal: 26.10.2004
Contract expiry: 25.01.2007
Win ratio: 54.1% W: 33 D: 13 L: 15
Total games/goals opposite LFC: 3 / 0
LFC league games/goals: 37 / 1
Total LFC games/goals: 61 / 3
Diao trained at Monaco's academy in Daquar, Senegal and impressed enough to be moved to Monaco's first team in 1995. Diao spent three seasons at Monaco but struggled to win a place in the starting 11 as the club enjoyed great success. He was transferred to Sedan in the 2000/01 season where he caught Houllier's attention and was described by his teammate as "an incredible force of nature, athletic, hard working, a great ball winner." Diao signed for Liverpool after the 2002 World Cup where he scored and got sent off in the group stages against Denmark but was back in the starting line-up against Turkey who beat Senegal in the quarter-finals. The boss of Senegal, Bruno Metsu, was a big fan of his midfield general: "He is a monster,'' Metsu said. "I call him the extra-terrestrial one. Salif is a player who makes matches complete. There was no doubt he would be one of the Senegal players to move on to a big club.''
Diao was no monster success at Liverpool. He made 22 starts and 18 substitute appearances in the 2002/03 season, his highlight being a goal against Leeds on 19 October that sent Liverpool to the top of the table. He had also scored in a 5-0 drubbing of Spartak Moscow two weeks earlier which was quite a novelty for the defensive midfielder who didn't score a single goal in 77 league games in France. Despite early promise Liverpool failed to capitalize on a second-place finish and finished 16 points worse off than in the previous campaign. Diao had acclimatized better than Liverpool's other summer buys; his compatriot El Hadji Diouf and Frenchman Bruno Cheyrou, by showing he was a tough player who played with his heart on his sleeve. Although Houllier had initially faith in Diao's ability it was clear that Steven Gerrard did not: "With Salif, I knew after a week of training that he wasn't going to be good enough," Gerrard said in his autobiography. The Senegalese admitted his situation was bleak in February 2004: "Houllier has changed his tactics and uses one ball-winner in midfield. It's fair to say this has been a blow to my chances."
After Houllier left in the summer Rafa Benítez loaned Diao to Birmingham City and Portsmouth, but injury problems made it easy for respective sides not to sign him. Diao joined the Potteries on loan in October 2006 and eventually signed a one and a half year deal with them in December 2007. Diao was by no means a regular at Stoke, but somehow he managed to convince the boss to sign him on again and again, also becoming an ambassador for the club to improve its links with African countries. Diao passed his thirty-fifth birthday during the 2011/12 season at the end of which he left Stoke, having turned down an offer to join their coaching staff to continue his playing career.