Saha claims that the Rooney will do whatever it takes to end his club's current slump and thinks he can handle the emotions of a momentous return to Old Trafford after spending over 10 years there as a player and becoming the club's all time top-scorer.
Rooney will make his first appearance as an opposition player against Man United in 13 years as Everton travel there looking to bring an end to a run of three straight losses in all competitions.
The former England striker is currently the only player who has scored for the Toffees in the Premier League this season and he will be looking to add to his two goals against Jose Mourinho's side following back-to-back 3-0 defeats to Tottenham and Atalanta.
Rooney returns to Old Trafford the day before a court hearing for a drink driving charge, but Saha doesn't expect this to affect him and says he will be totally focused on inflicting a first defeat of the season on United.
The former French striker said: "It's going to be a very emotional day for him I'm sure, his heart was for so many years at Old Trafford, but we have seen Wayne Rooney on many, many occasions in the very special moments and he has always reacted well.
"I think he has showed over the years that he is a very fortuitous player, able to handle any kind of pressure and able to perform.
"He has to perform for Everton and he will definitely be looking to score. He will want to win, he will want to score a goal as well. Yes I am sure that he will perform, he will try to score a goal or two and try to make this occasion special.
"[To train with] he was amazing, he's just a player that makes it easy for you. And because he's running really hard, he works really hard, he'll break his leg for you."
Saha, who had a successful spell at Everton after leaving United in 2008, is expecting a close contest between his two former clubs this Sunday and he believes Rooney will put his off-field distractions to one side to lift the negative feeling around Goodison Park.
"He must hurt, that's for sure," the 39-year-old added. "He's a human being, he's got emotions. But he's very strong mentally.
"You can't even imagine the pressure he has been under, to have all those people in your country on your shoulders and keep performing at the highest level. Sometimes I'm sure he's complaining about it because it can't be helpful.
"You wouldn't want to be Wayne Rooney for those kind of reasons because he's very famous, he's playing with passion in his game, but that kind of pressure, it's just on Rooney."