The Blues are understood to have made Telles one of their top summer targets, with the futures of Marcos Alonso and Emerson Palmieri both uncertain and Leicester City's asking price for Ben Chilwell considered too high.
The 27-year-old has been a key player for Porto this season, scoring 10 goals and creating nine more from left-back, but Sinclair believes that Frank Lampard would be better off targeting players who already have Premier League experience.
"Alex Telles is a good player, I like what I've seen of him but whether he has the ability to adapt to the Premier League is a different question. There is no other league like the Premier League, purely due to the competition in every game, week in, week out – there is no easy games," Sinclair told Genting Bet.
"That's why I'd prefer to see Chelsea sign proven players that have played in the Premier League before. You look at Emerson for example, terrific player before coming to the Premier League but he hasn't been able to lock down a position for Chelsea. It just shows how difficult it is to adapt and to acclimatise to the Premier League.
"You'd expect Telles to be able to handle the Premier League and do well but it's certainly not something that I take for granted, that a player who is playing well abroad can just come in to the Premier League, hit the ground running and continue.
"There have been rumours about Chelsea signing Ben Chilwell – if you had asked me six months ago, I would have said that he was the ideal left back for Chelsea but his form has dipped towards to the back end of the season, which has made me question him.
"You have to remember, it is a massive difference being a player at Leicester City and Chelsea. At Chelsea, you have the expectation of winning games every week, winning titles and European Cup competitions."
In all, Telles has registered 52 assists and scored 21 goals of his own in 183 appearances for Porto.