Chelsea boss Carlo Ancelotti has revealed he will try to sign a new defender if Alex fails to recover from knee surgery before the end of next month.

But Ancelotti insists he is not planning to do any further business during the January transfer window, despite seeing his squad fail to cope with injuries to key players in the last two months.

Brazil international Alex was ruled out for up to eight weeks after going under the knife at the start of the month.

His knee problems co-incided with an injury to captain John Terry, forcing Ancelotti to play Paulo Ferreira as a makeshift centre-half.

The move backfired spectacularly when Chelsea slumped to their worst home defeat for eight years against Sunderland.

Ancelotti last year famously vowed to run around the club's training ground if he signed a player in January but he was not willing to make the same promise 12 months on.

"If I have to bet, I can bet the opposite," he said.

"Until the 31st of January, if we are sure that Alex will have resolved his problem, we won't need another defender.

"We have to wait to see his condition.

"We can think about things, a new defender, towards the end of January. That would be the only position."

And that player could well be English, according to the Italian.

"Obviously, if you take an English player, you don't have a problem with the culture, the language," he said.

"Maybe they have advantages for this reason."

Ancelotti insisted it was pointless trying to sign a player to cover for the likes of Frank Lampard, who will make his first appearance for four months in tonight's crunch clash at Arsenal.

"In the market, there is no player capable of replacing Lampard," said Ancelotti, who has already dismissed reports linking him with Tottenham playmaker Luka Modric.

Chelsea have badly missed Lampard's goals in what has been their worst run in the league for more than a decade but Ancelotti defended the contributions of the 32-year-old's fellow midfielders John Obi Mikel, Ramires and Michael Essien, and forwards Didier Drogba, Nicolas Anelka and Florent Malouda.

He said: "Every player has different skills: Mikel is not able to score but is fantastic defensively; Ramires the same; Essien has, I think, his skill to score from outside the box but he was injured for a month, so his condition has not been so good.

"I can say that Drogba scored 40 in one year.

"I don't have to look at this moment and judge the performances of the players.

"If you have to judge Drogba, Anelka or Malouda now, they haven't scored. But Malouda was one of the more impressive players at the start of the season.

"The ability of the coach is not to judge moment by moment. If you do this, you're up and down all the time."