Torres will have a scan tomorrow to determine the extent of the hamstring injury suffered during the goalless draw with Aston Villa in the Barclays Premier League.

He pulled up suddenly during the first half and immediately signalled he was unable to play any further part in the game.

The Spain international now has a two-week international break before Liverpool return to action against Manchester United and then, in the Champions League, Marseille.

Benitez said: "We will have to see what the scan shows tomorrow. When you lose Steven Gerard and then Torres, it is always a problem.

"We will have to see the extent of the injury. If it is like Gerrard's, it could be 10 to 15 days and he may only miss one game.

"We will just keep our fingers crossed that it is nothing too serious."

As regards Riera, Benitez said: "I am hopeful the deal will be done tomorrow. The deal is nearly done. I have confidence it will go ahead. Bringing in Riera will give us a bit of balance."

Benitez admitted the game with Villa could have gone either way as Liverpool surrendered their 100% league record for the campaign.

He said: "It was a top game. We could have won but we also could have lost. One point is good for both teams."

Villa manager Martin O'Neill was pleased to register his side's first clean sheet of the season after conceding five goals in the previous two league games with Manchester City and Stoke.

He said: "We would usually be more free flowing than that. We normally create more chances than that.

"We have kept a clean sheet which is something pretty unusual for us.

"I felt beforehand that if we did that, we would win the game because even the very best sides will struggle to keep us at bay for 90 minutes.

"We've produced one glorious piece of football from which we should have scored. But Liverpool are a class side.

"We limited them to very few chances and we think we can improve even more. We want to try and get better."

O'Neill praised the performance of Gareth Barry who came close to moving to Liverpool this summer.

He said: "Gareth did very well. He has had a lot to cope with during the last few weeks.

"It didn't bother him at all and I'm delighted to have him for the foreseeable future."