Last season's Champions League winners are in an all-London fight for third and fourth place, with one of Chelsea, Arsenal or Tottenham poised to miss out on a place among Europe's elite next season.
"As soon as you can win some games in a row you have momentum and confidence and it is easier," Benitez said on chelseafc.com. "We are not doing too many things in a different way but we are more convinced that we can beat anyone."
He added: "We are creating chances and we are controlling the games. Overall it is a good period, the team has more confidence and that is the key."
The consequences of finishing fifth are unthinkable for the Blues and Benitez believes his side will qualify for the Champions League with wins over United and Spurs.
"Every single game will be important for us," added Benitez, whose side play Benfica in the Europa League final in Amsterdam on May 15.
"To get three points in every single game will be massive. We're so close.
"We know if we can get these three points [against United] and against Tottenham, we'll be in the top four."
Source: PA
Source: PA