The 37-year-old Senegal icon is not fondly remembered at Anfield and he has spoken out against the Reds in an interview with French television.
The former Senegal striker joined the Reds in 2002 following a bright World Cup campaign in which his nation claimed an opening-day upset over incumbent champions France.
However, the 15 million Euro (£10million) signing - according to Transfermarkt - scored just six goals in 80 appearances over two seasons.
He was then shipped out on loan to Bolton Wanderers and went on to join them permanently.
Aside from Diouf's poor performances, there were also reported off-the-pitch issues, with former captain Steven Gerrard slating the forward in his autobiography, as serialised by the Liverpool Echo.
The 37-year-old has now slated his former employers, bringing up his time at Liverpool when asked by French television station RMC Sport about which football club he regretted playing for the most.
“I can say today that the shirt that I regret wearing the most was Liverpool’s,” said Diouf.
“Because if I were to do that part of my career again, I would have gone to FC Barcelona or Manchester United. At the time, they wanted me too.”
Despite the controversy surrounding Diouf, he won 70 caps for his country, was twice named African Footballer of the Year and also named in Pele's FIFA 100 top players list.
After his time at Bolton, the Senegalese moved to Blackburn Rovers and then went on loan to Rangers, Leeds United and Doncaster Rovers.