Cristiano Ronaldo reiterated to Manchester United executives this week his preference to join another club this summer, according to The Athletic's Laurie Whitwell.

Per that report, Ronaldo's agent, Jorge Mendes, is "working to establish exit routes from Old Trafford, and The Athletic understands talks have been held with Sporting Lisbon," Ronaldo's former club that finished second in Portugal's Primeira Liga last season and will have Champions League football this year.

A transfer to his first professional club may not be realistic, however. As Whitwell noted, "finding the finance for such a move—including covering his high wages—would be complex and it is said head coach Ruben Amorim has reservations about bringing Ronaldo into his team given the huge change in dynamic the 37-year-old would inevitably cause."

Additionally, Manchester United executives remain uninterested in selling Ronaldo this summer, per that report.

But while Ronaldo reported Tuesday to United for medical testing, he has been training away from the team and didn't join them on the preseason tour. With the club's Premier League season opening Aug. 7 against Brighton Hove & Albion, Ronaldo's absence has become a major concern.

That is compounded by the fact that new manager Erik ten Hag is attempting to institute his system ahead of the season. Ronaldo hasn't worked with his teammates or his new manager on the pitch, though he has been training in Portugal, per Whitwell.

Ronaldo's combination of wages and limitations on the pitch—while he scored 18 goals in 30 Premier League appearances last season, he doesn't offer the defensive work rate needed for the popular high-pressing style many managers want to play—have seemed to keep high-profile clubs at bay this summer.

While Ronaldo wants Champions League football, clubs like Atletico Madrid, Bayern Munich, PSG and Chelsea have reportedly—or in some cases, very publicly—declined to pursue him.

It's all a major concern for United, which already is thin up top at the striker position and hoping to avoid another disastrous campaign like last season in which it finished sixth.

Some resolution on Ronaldo's situation would go a long way toward aiding that effort.