The 37-year-old is believed to be considering leaving Manchester United in the current transfer market due to concerns over the club's ambition.
The Red Devils are said to be adamant that the forward will not be leaving, but the club would find it difficult to keep hold of him if he pushed for a departure in the coming weeks.
According to The Sun, Sporting have been in touch with the Portugal international to express an interest in bringing him back to the club in the current window.
"Sporting know that Ronaldo loves winning trophies. That looks a long way away at United at the moment and time is running out for Ronaldo," the newspaper quotes a source as saying.
"So what better way to finish his career than move back home and play in Portugal. It's a strong league and a great lifestyle. Senior officials have made enquiries and let Ronaldo know they are interested if he wishes to leave United."
Ronaldo joined Sporting at the age of 12, progressing through their youth system before making his first-team debut for the Portuguese giants in 2002.
The attacker's performance for the Green and Whites against Man United in the summer of 2003 convinced the 20-time English champions to bring him to Old Trafford ahead of the 2003-04 campaign.
Ronaldo went on to represent Real Madrid and Juventus before returning to Manchester last summer, and he enjoyed an impressive 2021-22 season for the club on a personal level, finding the back of the net on 24 occasions in all competitions, including 18 outings in the Premier League.
The Red Devils finished sixth in the Premier League, though, which saw them miss out on the Champions League for the coming campaign.
Man United boss Ten Hag is believed to view Ronaldo as a key part of his plans for next season, with the Portuguese demonstrating last term that he is still capable of scoring goals in the Premier League.
Chelsea and Bayern Munich are among the clubs to be credited with an interest in his services this summer, although the Red Devils have him on a deal until June 2023, with the option of a further 12 months.
Ronaldo is believed to be keen for Man United to sign a new forward this summer, with Edinson Cavani's departure leaving the Red Devils short of options in the final third.
Darwin Nunez had been strongly linked with a move to Old Trafford, but Liverpool ultimately signed the Uruguay international in a big-money deal from Benfica.
Man United will be back in pre-season training on Monday, but Ronaldo will not join up with the squad until July due to his involvement for Portugal in the UEFA Nations League earlier this month. body check tags ::