Chelsea consider signing back-up to Petr Cech

Rafael Benitez aware that Fernando Torres needs a rest

Demba Ba is expected to complete his long-awaited move to Chelsea today, having been at the club's training ground today for tests on the knee that caused him to fail a medical at Stoke City in January 2011.

The Newcastle United striker met with members of the Chelsea squad at Cobham and it is still hoped that he will be signed in time for the lunchtime deadline that will allow him to play in the FA Cup third-round tie on Saturday against Southampton. The competition has taken on greater significance since Wednesday's 1-0 defeat to Queen's Park Rangers in the Premier League.

Rafa Benitez's team are now 14 points behind the leaders Manchester United, albeit with a game in hand, and are facing a growing number of injury problems. There are suggestions that they may explore extra cover in the goalkeeper position with Petr Cech out for another two to three weeks with a groin injury.

His understudy Ross Turnbull played against QPR on Wednesday, having come on as a substitute when Chelsea beat Everton last Sunday. It was just his 12th start for the club in more than three years and beyond him is Hilario, the veteran Portuguese goalkeeper. Cech's injury is a concern for Benitez, who cannot afford for the 30-year-old to delay his return too long.

There are also worries over John Terry, who has not played for the club since the draw with Liverpool on 11 November when he sustained the bruising to his bone that has caused him such problems.

Frank Lampard, who was taken off against QPR, was reported tonight to be ready to leave the club when his contract expires in the summer. However, his agent Steve Kutner denied telling an Italian website that the 34-year-old midfielder would "certainly change team at the end of the season."

Benitez conceded that his players were starting to feel the effects of a punishing December in which they played nine games.

Torres, in particular, has started 31 games this season, more than any outfield player and as many as Cech, and Benitez conceded that the striker now needs a rest. Ideally, the club would play Ba against Southampton but that rests upon his registration being done in time.

Benitez said: "Fernando is one of the players who needs to rest. Two or three players have been playing too many games in the last weeks and months. Managing that was going well but against QPR it didn't work. Some of the players couldn't get to the level we were expecting. Without talking about names, if you have another striker you can play with two strikers if you need to. Or if you want to rest a striker then you can do that and at the moment we are a bit short."

Benitez defended his decision to pick Marko Marin against QPR, saying the team he selected should have been good enough to beat the bottom side in the Premier League. He said: "We cannot keep playing the same players every game. And if you're playing the team at the bottom of the table at home you have to trust your players. I trust them and thought it would be fine."