Radamel Falcao's recent injury history casts a huge question mark over his ability to succeed at Manchester United, according to former coach Rene Meulensteen.
The Colombia international suffered cruciate knee ligament damage last January and, after missing the World Cup finals, has made just three substitute appearances since returning, the latest coming in the 1-0 friendly defeat to Brazil in Miami last week.
Falcao has declared himself fit to make his United debut against Queens Park Rangers when the Premier League resumes this weekend, however, Meulensteen says expectations of the Monaco loanee should be tempered given the 28-year-old's recent fitness.
"Obviously Falcao has been excellent and is a world-class striker," Meulensteen, who left United in 2013, told talkSPORT. "The only reservation you have to have with him is -- because of his recent injuries -- is he still going to be able to produce that level we all know he's capable of?"
Though Danny Welbeck has moved to Arsenal the addition of Falcao leaves manager Louis van Gaal with a selection dilemma ahead of the new season with captain Wayne Rooney and Robin van Persie both competing for a place in the United attack.
Recent signings Angel di Maria, Juan Mata and Ander Herrera are among the other players also aiming to cement their place in Van Gaal's first team and Meulensteen says the Dutch coach will thrive with such an embarrassment of riches at his disposal.
"Every manager would be delighted to have such players in the squad, that's what you want," he added. "You need to have big players in the squad filled with a lot of quality and also you need to have the ability to change it at times without losing that quality.
"Louis [van Gaal] has been very clear on the system he wants to play, which is a little bit foreign to Manchester United to what they've always been playing.
"At the moment it hasn't worked yet and it will be very interesting to see whether he will remain tying to perfect the system or is he going to change the system in favour of the players he has brought in?"