Sesko has had a difficult spell since joining as the club’s biggest signing of the summer following his £74M from RB Leipzig.
The 6’5″ striker has found the net five times in 19 games for United and has been criticized for his lack of goals under managers Ruben Amorim and now interim boss Michael Carrick.
Now, speaking to Grosvenor Casinos, Saha has revealed that Sesko must change his mentality going into games and act like a striker at one of the biggest clubs in England.
"I think Sesko is starting to understand the Premier League more, the movement, his teammates, the tactics he has to play under, sometimes with the pressing, sometimes not, sometimes just being a fox in the box.
"He needs this kind of aggression a bit more, and arrogance. I think when we get that, Sesko is going to be one of the players who is really hard to play against. He just needs to be a bit more aggressive, not in a bad way, like tackles, but just believe in himself and have the guts to try and retry and not think twice.
"At this age, it's a very big task, but I think he has the opportunity to do it because there is not much competition for him upfront, so he has to do it.
"He has the opportunity to do it, but he has to do it because this is what the manager needs. He needs arrogance, a bit like Matheus Cunha can show sometimes, or Bryan Mbuemo.”
"When you have all the players really express this kind of confidence and arrogance, this is where any defence will, I think, in some way, become fragile."
Sesko has struggled to adapt to life in the Premier League since and may take Saha’s advice onboard heading into the weekend clash against Fulham as he tries to displace Bryan Mbeumo in the side.