Liverpool's poor home form continued with a 1-1 draw against struggling Manchester City at Anfield. Both goals came in the second half - former Liverpool player Craig Bellamy opened the scoring for Man City before Dirk Kuyt equalised late on to leave Liverpool seven points behind leaders Manchester United.
The Reds have now drawn six and won seven at home, while United have drawn just one and won 12 at Old Trafford.
"Clearly it's more difficult now," Benitez told the club's official web site. "We have to win against Middlesbrough and Sunderland and then we have to start thinking about winning at Old Trafford.
"I have confidence we can beat Middlesbrough and Sunderland and then it might be a different situation.
"It's not easy because United can win games even without playing well, but there are still 12 games. You cannot say everything is finished.
"Clearly if we want to reduce the gap we have to win our next games and then beat United."
Benitez added: "It was a bad result because we could have done better with the chances we had in the first half.
"We controlled the game but you have to score first. We conceded a deflected goal and that changed the game because they have pace and ability - things were more open so they were dangerous on the counter attack.
"After we scored the goal we had chances and could have won the game."