Romelu Lukaku will need to improve if he is to become a success at Manchester United, Ryan Giggs has told Sky Sports.
Lukaku, 24, has hit the ground running since his £75 million move from Everton, scoring three goals in six preseason games this summer, but Giggs insists he will need to get better if he wants to be a hit at Old Trafford.
He said: "Manchester United needed some new blood and the injury to Zlatan Ibrahimovic removed the question as to whether he was replaced. Romelu Lukaku will score goals, there's no doubt about that.
"He's still got to work on his first touch but he has already been scoring plenty at West Brom and Everton and will get more chances at Old Trafford.
"What he won't have experienced is the pressure of being a Manchester United forward. He wouldn't have felt that before and you can't get away with the odd mediocre performance."
Lukaku will be tasked with replacing the goals Zlatan Ibrahimovic scored last season having taken the former Paris Saint-Germain striker's No. 9 shirt.
Even with Ibrahimovic's contribution, United were still the lowest scorers in the Premier League's top seven last season.
There is still a chance Lukaku will get help from Ibrahimovic in the second half of the season if the 35-year-old recovers well enough from knee surgery to sign a short-term deal but, until then, Giggs says Lukaku will need help from his United teammates to share the responsibility in front of goal.
Last season, only Ibrahimovic reached double figures in the Premier League, with Juan Mata's six the next best.
Giggs added: "There were too many home games last season where we didn't take our chances but it's not just down to Lukaku, the rest of the team need to be contributing as well."