Nani has implored Manchester United to do all they can to ensure Cristiano Ronaldo stays at the club amid speculation linking him with a move away.
Ronaldo has reportedly asked to leave Old Trafford in this transfer window, with Chelsea rumoured to be among the early frontrunners for his signature before the Blues signed fellow forward Raheem Sterling.
Chelsea's new owner Todd Boehly was said to have held talks with the Portugal captain before the American and coach Thomas Tuchel opted to resist the temptation to launch a bid.
Bayern Munich, who have lost talisman Robert Lewandowski to Barcelona, were another side linked with Ronaldo, but Julian Nagelsmann and chief executive Oliver Kahn were quick to rule out a move.
Erik ten Hag has repeatedly insisted Ronaldo is not available for transfer, though, with the new United coach making it clear he wishes to keep the 37-year-old at the club.
While United failed to secure Champions League qualification last season, reportedly a decisive factor in Ronaldo's dissatisfaction, former Red Devils winger Nani has urged his compatriot to stay with Ten Hag's side.
"I hope [he stays]," said Nani, who recently signed for Melbourne Victory and played a late cameo in their 4-1 friendly defeat to United on Friday.
"He's an important player and a player who always makes a difference. I hope he's in a good mood to help the club so hopefully [he'll stay]."
Nani also revealed he had tried to contact Ronaldo to discuss his future, but the five-time Ballon d'Or winner is busy on holiday.
"When he's on vacation he doesn't answer the phone to anybody," added Nani, who won four Premier League titles and one Champions League at United. "I tried to talk to him, but he said: 'I'm so busy now, we'll talk soon.'"
United will hope to have Ronaldo available to call upon when they begin their Premier League campaign at home to Brighton and Hove Albion on August 7.
