Sinclair has concerns about Telles' lack of Premier League experience.
He told GentingBet: "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.
"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."