Mane and Lewandowski are two completely different footballers, i don't think Sadio Mane is a striker, yeah he can play in the number 9 position, but he feels more comfortable coming from the flanks like he did in Liverpool, Lewandoski is a number 9, a player that was created to score goals, just look at his stats, there is no comparison between Lewandowski and Sadio Mane when it comes to scoring goals, so it is not about Mane not being able to handle any pressure, you shouldn't expect him to recreate Lewandowski's numbers in front of goal, he has his other stronger areas.