The Senegal star scored in Southampton's 3-1 win in the capital last season after claiming a 1-1 draw there the year before.
The 24-year-old has also started this term in impressive form and he hopes to keep that going tonight.
He told Sky Sports: "I can say I've never lost [at] Chelsea and hopefully that's going to continue.
"Chelsea are a big team and we will respect them. I think we will be ready for the game and will give our best for the club and the fans.
"Chelsea are one of the big clubs, but I think we also have a good team this season with great players and we have a good manager.
"I think we will be ready for the game."