Guirassy was heavily linked with a move to the Premier League this summer after managing nine goals and one assist in 21 games for Amiens last season.
West Ham appeared to be particularly keen on his signature and were named as suitors throughout the summer, with Tottenham and Crystal Palace also among those thought to be keen.
A move to England did not happen, though, with the striker instead electing to remain in France and join Rennes in a £13.5m deal.
This week saw featuring against Chelsea in the Champions League, and now Williams has revealed he could have actually been turning out for Frank Lampard’s side.
“He refused to go to Chelsea during the last window,” he told he told Le Parisien.
“Serhou made a sporting choice when he could earn more money with the London team.
“He wanted to continue in a club where he was sure to have some playing time and not relive an experience like the one in Cologne where he was a substitute.
“The choice fell on Rennes because coach Julien Stéphan assured him that he was counting on him.”
That’s a move that certainly makes sense for Guirassy, who only has to look at Michy Batshuayi to see that moving to Chelsea wouldn’t have been a smart move.
With Timo Werner also arriving at the club, Tammy Abraham continuing to impress and Olivier Giroud around too, it’s hard to see where he would have gotten game time this season.
That’s something he is enjoying at Rennes, with five goals in 12 games so far suggesting that turning down the money was the correct call.