The star forward returned to Old Trafford last summer, 13 years after leaving for Real Madrid for a then-world record fee, but it did not prove to be the glorious homecoming he had hoped.
Ronaldo scored 24 goals in 38 games in all competitions but the team struggled to a sixth-placed Premier League finish amid criticisms of his impact on their pressing abilities and general cohesion.
Portuguese forward Cristiano Ronaldo (above) is reportedly ready to quit Manchester United this summer over their lack of progress in the transfer market under new boss Erik ten Hag
Former Ajax manager ten Hag (pictured) took over in April and is aiming for a big squad rebuild
The Portuguese veteran, 37, has a year left on his contract and both he and new manager Erik ten Hag, who replaced interim boss Ralf Rangnick in April, have spoken with excitement of another season after the Dutchman implements a squad rebuild.
But despite interest in Darwin Nunez, who has joined Liverpool, Barcelona midfielder Frenkie de Jong and Ajax winger Antony, the club are still yet to make a single signing.
And according to Portuguese outlet Record, a heavily frustrated Ronaldo is ready to quit the north-west side due to their apparent lack of transfer ambition.
The club, and Glazer owners (pictured), are yet to complete a single transfer this summer
And the former Sporting Lisbon and Juventus star has reportedly issued the club an ultimatum – ‘up your game or I’ll leave’.
Ronaldo is said to have informed his inner circle that a continued lack of transfers would see him start looking for another club.
He had previously told the United website: ‘What I know about (ten Hag) is he did a fantastic job for Ajax, that he’s an experienced coach. But we need to give him time.
The Red Devils were interested in Benfica’s Darwin Nunez, but he eventually joined Liverpool
Ten Hag and United have been heavily linked to Barcelona’s Dutch midfielder Frenkie de Jong
The boss is also keen on signing Brazilian winger Antony (pictured) from the Eredivisie side
‘Things need to change the way he wants. I hope we have success, of course, because, if you have success, all of Manchester is going to have success as well. I wish him the best.
‘We are happy and excited, not only as players, but the supporters as well. I wish him the best and let’s believe that, next year, we are going to win trophies.’
Ajax defender Jurrien Timber has already turned down a move after former United boss Louis van Gaal warned him off it, while Derby youngster Malcolm Ebiowei has reportedly spurned United in favour of Crystal Palace.