Fernando Torres and Steven Gerrard both scored that afternoon and, after struggling for fitness and form for much of this campaign, the pair appear to be approaching their best form.
Both were also on target in Thursday's 3-0 Europa League win over Lille, Torres netting a second brace inside three days to take his tally for the season to 17 in 27 games.
And Benitez said: "If Torres and Gerrard are fully fit they can change games and win games. The top class players want to play against the top sides and against other top class players. Both will enjoy it hopefully and it will be a challenge for them.
"If the team is working hard and they are fine, then we can beat anyone. Everyone working hard makes us much more difficult to beat.
"We are doing better now. We have players coming back from injuries, they are fitter and can help us and hopefully we can keep this form until the end of the season.
"For us, Fernando is very important. If he had been fit all this season, then the gap to the top would have been smaller, that is clear. If Fernando is fit, he’d score in a lot of games. It would have been a different season for us."
Asked if he would swap Torres for United's talismanic Wayne Rooney, Benitez added: "Not really. Fernando is a fantastic player, so is Rooney too. There’s no doubt Rooney is very, very good. But Fernando is our player, the fans love him and we want to keep him for a very long time."
Liverpool are hopeful Alberto Aquilani will have recovered from the virus that ruled him out on Thursday, while Maxi Rodriguez is available after being ineligible in Europe.
Benitez, meanwhile, says he has no regrets over his war of words with Sir Alex Ferguson last season, but laments having been unable to resume the mind games this year.
"I understand that the last year we both said a lot of things but this year is different," he said. "They are at the top of the table, we have to do our job if we want to be in the top four, the main thing for me is to concentrate on my team.
"Last year is the past so we have to concentrate on the future. The future is to be ready for this game and try to do your best. If you have a good preparation then you can win.
"But I don’t talk with him."
