It's no secret that Antoine Griezmann is Manchester United's number one target this summer.

The Frenchman has made a name for himself at Atletico Madrid as one of the most prolific forward's in Europe and a number of clubs are understood to be interested in him.

With Zlatan Ibrahimovic not a long-term option for Jose Mourinho, with the Swede still yet to agree an extension to his one-year deal, Griezmann has been identified as the perfect man to lead United's attack, with Wayne Rooney set to leave in the summer.

SIGN UP NOW

Want to become a GMS writer? Sign up now and submit a 250-word test article: http://gms.to/haveyoursay4

The club have become confident that their £89 million target will move to Old Trafford in the summer, after three years in the Spanish capital, with Mourinho now looking to steer the club back to being a title-winning team in the post-Sir Alex Ferguson era.

But the Red Devils must have some alternative/ back-up options up their sleeves as The Sun have revealed that Griezmann has one major concern over this potential move to the north-west of England in the summer.

The France international is understood to be thinking twice about his proposed moved to United, and is concerned that the club could miss out on Champions League football for a second consecutive season.

Mourinho desperate to acquire Atletico star

Mourinho is understood to be desperate to sign the forward, but with his side currently four points short of a Champions League spot - following draws at home to West Brom and Everton - the Portuguese's side are proving to be far from convincing.

Indeed, it would be Griezmann's firepower - with his 14 La Liga goals and seven assists - that would help the Red Devils to be top four contenders again. But Atletico's star man wants to be ensure that he will be competing in Europe's elite club competition next season.

Griezmann's representatives have already contacted the club to raise the issue, while it had been thought that Paul Pogba's presence at Old Trafford would help in luring his compatriot away from the Vicente Calderon to the Red side of Manchester.

Chelsea could hijack Griezmann transfer

United's best chance of Champions League football looks most likely to come via winning the Europa League, but even that will remain to be a big ask for Mourinho's men who are fighting on two fronts.

And Mourinho could face losing his no.1 target to Chelsea, who are also interested in the Atletico man, and would be able to guarantee Champions League football and the attractive prospect of joining the Premier League champions.

Securing Champions League football will not only represent a relatively successfully campaign for Mourinho, but could have a crucial impact on his ability to acquire his transfer targets this summer.

These final few weeks of the season could be a defining period for United.