Belletti arrived from Barca for £4million after Chelsea ended their interest in Sevilla's Daniel Alves because of the inflated price tag of more than £25million.

Belletti, 31, will go straight into the squad for tomorrow's home game with Portsmouth and while Mourinho insisted there would be no more new faces, he also made it clear he was willing to trim his squad.

Chelsea now have Glen Johnson, Lassana Diarra and Paul Ferreira as support right-backs to Belletti and it seems certain that one of them will leave before the closure of the transfer window.

The favourite to move on is Arsenal target Diarra. He has already indicated his desire to leave and with the success of Mikel John Obi in midfield, Mourinho may be ready to grant his wish.

Mourinho said: "First of all, this new player gives me what I need which is a closed door in my dressing room. That is very important for me.

"The market is open until August 31st but not for us. We have the new signings we fought for and we have the balance in the squad.

"But I want my squad to be just a little bit smaller. We have 27 players because Belletti comes in but Arjen Robben goes out, and if we can, we will go down to 26.

"Our squad is a very balanced one. We have two players for each position and the right-back position is a position where we have more than two.

"For the interest of the players, because everyone likes to play and not just be part of the squad, if clubs show a real interest in one of our players and our player shows interest in leaving for a better situation, that is okay.

"But it is not a drama for me to keep 27 because they are all good players, they are useful and the season is long."

Mourinho would not indicate which of the right-backs he was prepared to let go but it is unlikely to be Ferreira.

Mourinho added: "Paulo is a player that I trust very much. Paulo is with me for six consecutive years and everything that I have won, he has won with me.

"From the defensive point of view he is a safe player. The reason why I wanted to bring in a different right-back is Chelsea, this season, is a different team, as everyone can feel.

"There is a different philosophy of playing so I felt I needed something different on the right, but no doubts, Paulo is a player that I love and I trust.

"Belletti brings what we believe we need, a pure right-back, not an adaptation any more like we did so many times with Diarra, Michael Essien and Shaun Wright-Phillips in that position.

"So we have an attacking right-back and not an ordinary one. He has played in two of the biggest teams in the world - the Brazil national team and for Barcelona. In Brazil he was world champion and in Barcelona he was not just Spanish champion but also European champion."

Belletti has enjoyed World Cup success with Brazil and scored in the Champions League final win against Arsenal in 2006.

His experience allowed Mourinho to switch his attention to the Barca right-back when Sevilla priced Alves out of the market - insisting that Belletti was the "best player at the best price".

Mourinho added: "Belletti has experience of playing in big teams so he is not scared to play at Chelsea.

"Was he the first option or the second option? For me the point is always the same, the best player is always the best relation between quality and price.

"Belletti is a very good player and the relation between his quality and the price makes him the best."

The Brazilian paid tribute to Mourinho and immediately set his sights on Champions League success with his new club.

Belletti said: "Everybody knows Mr Mourinho is one of the best coaches in the world. When he goes for a player, he knows what he wants and he goes for quality. I am sure Chelsea will only be successful under his direction.

"When you play for a team like Chelsea, you always go into games thinking about winning.

"The philosophy is to win every competition we are in so I hope we can win that one. Why not?"