Former Sporting Lisbon director Paulo De Alvandro believes it is "inevitable" Louis van Gaal will want Nani back at Manchester United.
Nani has enjoyed a spectacular campaign since re-joining Sporting on a season-long loan and was recently voted the Portuguese League's player of the season so far.
His form and United's lack of wide options have fuelled reports suggesting the club are looking to activate a clause to bring the player back to Old Trafford in January.
Both Nani and Sporting have claimed they are unaware of any such clause in his deal, while Alvandro insists the United boss now regrets his decision to allow the player to leave.
"It is inevitable that Manchester United will want the player back at the end of the season," Alvandro was quoted as saying by A Bola. "Van Gaal will be sorry to not have gambled on him sooner."
Despite signing a new five year deal at United last summer, Nani fell drastically out of favour under David Moyes last term, making just seven league appearances during the 2013/14 season.
His revival in Lisbon however could breathe life into his career at Old Trafford. United may look to add another winger to their ranks in the winter transfer window with van Gaal's recent team selections suggesting he now favours a system using two wide men as opposed to the midfield diamond used earlier in the season.
As a result, Angel di Maria has been deployed in a wide position in recent games where he has struggled to replicate the stunning form that marked his arrival at the club.
Should Di Maria be restored in a central positon, van Gaal may consider strengthening his wide options, although Nani is unaware of any clause that could see him return to his parent club to fill that void.
"I think there is no clause but I leave that for the others to solve," Nani said earlier this month. "It is always good to feel the affection of the fans. They want me back because they recognise that I am in good form and can be an asset for the club.
"That is football. Sometimes we are praised and sometimes we are criticised."