RAFAEL BENITEZ has warned Manchester United and Chelsea that Liverpool will improve in the second half of the season, although he admits that even one mistake "can be massive" in his club's quest for a first league title in 19 years.

The Premier League leaders' nerve and inexperience at the summit were questioned by United's manager, Alex Ferguson, this week and the Chelsea midfielder Frank Lampard said both Liverpool and United had failed to capitalise on the Blues' run of two wins from seven league games.

Benitez, however, believes that his team, who have lost only one game this season, are yet to realise their full potential. "I believe we can still improve," said the Liverpool manager, who is expected to return to the dugout at Stoke on Saturday after a recent kidney-stones operation.

"Martin Skrtel has not been playing, Mascherano has been playing much better in the last few games, Gerrard is improving now; we have Torres coming back now too.

"I think we will have more options in the second half of the season and more competition for each position. That can be important."

The return of Torres and Skrtel, who have recovered from a hamstring and cruciate injury respectively, presents Benitez with the dilemma of integrating them into an already functioning unit. It is a welcome problem for the Spaniard, admittedly, but he accepts that pursuing the title rather than merely Champions League qualification means he no longer has any margin for error with his selections.

"Clearly we are in a much better position than in past seasons. We are doing what we did before and analysing all the same details," he said. "The difference now is that you know if you make a mistake it can be massive, so you have to consider everything.

"Torres needs minutes on the pitch. It is a problem because the team is doing well. Some players you have to keep their momentum, but Aurelio, Skrtel and Torres need to play too. So to keep the balance will be difficult."

That strength in depth underlies Benitez's view that Liverpool will be quiet in this transfer window, with the exception of offloading Jermaine Pennant, who is considering an offer to join Milan and encouraging Daniel Agger to sign a new contract.

"It is difficult to buy in January. If you bring in new players then they need time to settle and if you sell players then maybe you will lose something," the manager said. "We don't have any clubs asking for our players. It is important to keep the squad together, although you cannot guarantee you won't sell anyone or sign anyone."

Meanwhile, Barcelona have denied reports that Manchester City have lodged a big-money bid for Yaya Toure. The Premier League outfit have made no secret of their desire to bolster their squad during the January transfer window and can boast the substantial financial backing of the Abu Dhabi United Group.

City have already been linked with a host of top names, with manmager Mark Hughes admitting he has keen to get a further five fresh faces on board over the coming weeks.

Newcastle United are expected to renew their interest in the Rangers midfielder Barry Ferguson after the Glasgow club indicated that they were willing to let their captain leave for about €3.3 million.

Newcastle's manager, Joe Kinnear, is desperate to strengthen his small squad but has been frustrated in the transfer window because the limited budget available to him - he is thought to have less than €11 million to spend - means he has been unable to secure any of his targets.

His options will be further limited by the absence of Obafemi Martins, who will undergo hernia surgery on Monday. Central midfield is of particular concern in the Newcastle squad and, with Ferguson available for significantly less than first thought, the 30-year-old Scotland international may become Kinnear's first signing at St James' Park.

Newcastle may face West Ham on Saturday with only one fit central midfielder, Geremi. With Nicky Butt suspended and Joey Barton at least a month away from returning after a knee injury, Kinnear's problems increased this week when Danny Guthrie went down with flu. "The people we have available are not regular starters and some not orthodox centre-midfield men, so it's serious," said Kinnear.

"I've made this statement to the owners so that they are aware of the situation. The people that we'll have on the bench against West Ham are only kids."

There was some good news for Kinnear yesterday as Shola Ameobi extended his contract for another three years.