Sporting Lisbon have reportedly been in touch with Manchester United to discuss the possibility of re-signing Cristiano Ronaldo on a free transfer this summer.

The Portugal international has been at the centre of one of the most high-profile transfer sagas of the current window, having allegedly told Man United at the start of July that he wants to leave this summer.

Ronaldo has been involved in his side's opening two matches of the 2022-23 Premier League campaign, but he seemingly remains determined to leave before the deadline, with the forward desperate to once again play in the Champions League this season.

Bayern Munich, Chelsea, Paris Saint-Germain and Real Madrid are among the clubs to reject the chance to sign him this summer, while AC Milan and Inter Milan have also allegedly snubbed a move.

There has been talk over a return to Sporting in recent weeks, though, and according to The Independent, a move to the Portuguese giants is now a serious possibility.

The report claims that the Green and Whites have been in touch with Man United to discuss the possibility of bringing the Portuguese back to the club on a free transfer.

Sporting would allegedly be able to re-sign Ronaldo providing that they did not have to pay a transfer fee, but it remains to be seen whether the Red Devils would be prepared to let him depart on a free transfer, with his contract running until next June, and there is also the possibility of a further 12-month extension.

Ronaldo joined Sporting at the age of 12, progressing through their youth system before making his first-team debut for the club in 2002.

The forward's display for the Lions against Man United in 2003 convinced the 20-time English champions to bring him to Old Trafford, and he starred during his first spell at the club.

Ronaldo went on to represent Real Madrid and Juventus before returning to Manchester last summer, and he scored 24 times in all competitions last season, including 18 in the Premier League, but the Red Devils finished sixth, meaning that they will not play in Europe's elite competition this term.

Sporting will play in the Champions League this season, though, having finished second in their domestic table last term, which secured an automatic spot in the group stage.

Ronaldo is 15 goals ahead of Lionel Messi at the top of the scoring charts in the European Cup, netting 140 times in the competition, and it is understood that his desire to stay clear at the summit is one of the main reasons why he is so determined to continue playing Champions League football this season.

The Portuguese's agent Jorge Mendes is said to have held talks with a number of Champions League clubs over a move for his client this summer.

Mendes's attempts to secure an exit have thus far been unsuccessful, but Sporting are now seemingly firmly at the head of the queue for his signature.

Ronaldo trained with Man United on Wednesday as usual, with the 20-time English champions preparing for their next Premier League game against Liverpool on Monday.