Andre Villas-Boas has insisted Gary Cahill is ready to be thrown in at the deep end in Chelsea's crunch clash with Manchester United.

Blues boss Villas-Boas confirmed there was a "big possibility" Cahill would finally make his debut in Sunday's Premier League game at Stamford Bridge.

That would be a real baptism of fire for the £7million January signing, who has not kicked a ball in anger for exactly a month but could now come into a defence shorn of its two star men.

Having rejected the chance to blood Cahill in Chelsea's recent matches against Norwich and QPR, Villas-Boas then surprised many by leaving him out for Tuesday's trip to Swansea after captain John Terry was ruled out through injury.

Terry has failed to recover in time for Sunday's game, while Ashley Cole is suspended after being sent off at the Liberty Stadium.

Nevertheless, Villas-Boas was confident Cahill would be able to help fill the void.

"I think he has been ready from the start, to be fair - he's trained magnificently well," said the Portuguese, who reiterated the decision not to play Cahill against Swansea was based on the past performances of his other defenders.

Villas-Boas admitted the loss of Terry and Cole was "massive" because of their partnership on the left side of Chelsea's defence.

"It's a blow more in the sense of those two not being there to link together," he said as he mulled over whether to hand young left-back Ryan Bertrand his full Premier League debut on Sunday or move Jose Bosingwa from right-back.

Neither is a an ideal replacement for Cole, who misses a league game for the first time in 65 matches and would have been the Blues' best chance of stopping United winger Antonio Valencia.

The Ecuador international has been back to his best in recent weeks, one of several reasons why Villas-Boas believes the champions now to be favourites to retain their title.

"I think they will be the ones to beat," he said.

"This distance to Man City is equal to nothing and, for me, they will be the main favourites."

Villas-Boas has virtually written off Chelsea's title chances but was adamant they would finish in the top four.

"I don't think we'll finish below fourth spot," he said, adding he was convinced of that.

That conviction will be tested if the Blues do not start scoring more goals, and especially if Fernando Torres' drought continues.

Villas-Boas said: "Off the field, mentally he is ready, he knows his responsibility, he knows what he has to do.

"On the field and on the training ground, we try and work on his movement. That's the only thing we can do and we have been for quite some time.

"I think eventually we could say that a goal will trigger it all but we have to wait and see because there needs to be continuity after that."

If not, Torres will quickly lose his place again when Didier Drogba returns from African Nations Cup duty.

The Ivory Coast star was reported this week saying he was still open to staying at Chelsea beyond this summer but Villas-Boas would not be drawn on the prospect of reopening contract talks when the striker gets back from Gabon and Equatorial Guinea.