The 22-year-old spent five years with the Blues after joining from Bristol Rovers as a 16-year-old, but found first-team opportunities hard to come by.
Sinclair made just 14 appearance for the Blues and was loaned out to Plymouth, QPR, Charlton, Crystal Palace and Birmingham, before making the decision to leave permanently in the summer of 2010.
His move to Swansea worked out better than the England Under-21 international could have hoped, as Sinclair scored 27 goals to help the club secure promotion to the top flight, before adding six goals this term.
The winger found the target from the spot in Swansea's last home game, a superb 3-2 win over Arsenal which followed an excellent 1-1 draw with Tottenham.
And with Chelsea rounding out the trio of Liberty Stadium fixtures against London's top clubs, Sinclair is desperate to claim another big scalp.
"It would be brilliant if we can beat them," he said. "We have drawn with Tottenham and beaten Arsenal and if we can get three points this would be another big game to win.
"It would be amazing, and obviously for myself it would be one of the best wins of my career."
And Sinclair has cited the belief gained from that stunning success against the Gunners as key if Swansea are to pull off another upset, and gain revenge for the 4-1 defeat they suffered at Stamford Bridge in September.
"Once you have that belief you always go into every game feeling you have a chance and if we play like we did against Arsenal we will give every team a fight, and try to win," he said. "The defeat at Chelsea was early doors, everyone was trying to settle into the Premier League, but we have learnt so much more since then and we have improved.
"The team in Chelsea won't be worried about Swansea they will just come down and play their football. It will be their manager's job to explain the way we play but they won't know how we've improved since the first time we played them."
Chelsea will travel to south Wales without John Terry after the England captain was ruled out by a knee injury.
Swansea, meanwhile, will restore a host of players to their line-up having opted to make changes for the FA Cup exit at Bolton.
Swansea and Manchester City are the only sides not to have suffered back-to-back Premier League defeats this season, but the Welsh side will need to avoid losing to the Blues to maintain that record.
And Swansea boss Brendan Rodgers knows a stern test will await his side.
He said: "We know it s a tough ask but we have a great belief here and we want to continue with that."
