Senna wants his side to win so that they can finish top of Champions League Group E.
The Spain international almost joined Manchester United in 2006.
“Cristiano Ronaldo is one of the best players in the world in recent times but we are not obsessed with the Portuguese,” Senna told Setanta Sports.
“This would be to commit a big mistake because United have people that are dangerous in every position.
“A game against Manchester United is never easy. Firstly, because they are the champions of Europe and, secondly, because of the players they have.
“But after a draw at Old Trafford our spirits are high and it will be possible to win at home tonight.
“We know that we are within a draw of reaching the next round, but our dream is to win against United and finish as group champions.”