The former Senegal international was hot property back in 2002, with Gerard Houllier moving early that summer to secure his signature in a £10 million ($13m) deal.
Diouf went on to star for his country at the World Cup finals after signing for the Reds, with much excitement surrounding his arrival at Anfield.
He was, however, to flop badly, recording just six goals in his debut campaign and none in his second.
Quizzed by RMC Sport on his biggest regret, Diouf said: “I would say Liverpool.
“Because if I had the chance again I would go to Manchester United or Barcelona. At the time they wanted me also.”
Diouf never got close to attracting such interest again after linking up with Liverpool, with the creativity he showcased in France with Lens proving difficult to reproduce in England.
He did still enjoy a productive career, though, making close to 500 appearances at club level and earning 70 caps for his country.
He was twice named African Footballer of the Year and is held in the highest regard by those in Senegal.
That success means that he is well placed to pass comment on the emerging stars of today, with Paris Saint-Germain striker Kylian Mbappe among those to have caught his eye.
Big things are expected of a teenage talent who finished fourth in the 2018 Ballon d’Or vote, but he has been warned against taking inspiration from a club colleague at PSG.
Diouf said: “If I was to give Kylian Mbappe one piece of advice, it would be to not be like Neymar and more like Cristiano Ronaldo.”
Mbappe has netted 14 times so far this season, with that return placing him ahead of Ronaldo’s 11-goal haul at Juventus and one behind Neymar’s return for PSG.