Roger Federer could ditch Nike to sign a $39 million per-year decade-long deal with Uniqlo, according to reports.
The Swiss star has sported Nike clothing for his entire career and the American company owns the legendary "RF" logo, The Sun reports.
Reports originating in Swiss press report the 36-year-old has reportedly already signed a deal with the Japanese company, according to The Express.
Federer signed his first contract with Nike in 1994, but the long-term partnership could now be coming to an end.
His previous deal expired on March 1 and he can now boost his annual income by almost 30 per cent.
Uniqlo sponsored Novak Djokovic until 2017 and they currently work alongside Japanese star Kei Nishikori.
The 20-time Grand Slam champion could wear his new sponsor's clothing during the upcoming Wimbledon tournament.
But the Japanese company do not produce tennis shoes, so he will have to look elsewhere for that.
Throughout his time with Nike, Federer created the instantly recognisable "RF" logo.
But this is owned by the American company and it is expected that he will be re-branded by Uniqlo.
Despite the speculation, he arrived to the Stuttgart Open wearing a Nike T-shirt, shorts, trainers and a headband.
Federer decided to skip the clay court season and the French Open to prepare for Wimbledon.
The 20-time grand slam champion is in line for a dramatic payday.
According to reports, Federer's record 10-year sponsorship agreement with Nike - which expired earlier this year - is the wealthiest in the sport's history, worth more than $US120 million.
However, even that deal is dwarfed by some of Nike's other recent sponsorship agreements with NBA superstar LeBron James reportedly signing a lifetime deal with the apparel giant on a deal reportedly worth somewhere between $500 million and $1 billion.
According to Forbes, Federer already earns more than $65 million per year in endorsements alone - enough to keep him at No. 7 on the list of sport's highest earners.
He remains one of the most marketable athletes on Earth and he appears to be testing exactly what that marketability is worth on the open market.
Djokovic left Uniqlo last year to take up a lucrative five-year-deal with Lacoste.
Rival Rafael Nadal's five-year $50million deal with Nike also expires at the end of this year.
The 2018 French Open champion has other things on his mind right now after again closing in on Federer's grand slam record.
His record 11th French Open crown saw him take his grand slam haul to 17 major titles.
Despite this, Nadal has insisted he is not actively pursuing his grand slam rival.
The 32-year-old world No.1 earned a 6-4 6-3 6-2 over Austria's Dominic Thiem to retain his Roland Garros crown despite complaining of a wrist and finger injury in the third set.
The Spaniard remains confident and ambitious to win more and says he isn't concerned about his age or chasing history.
"Winning here after having the clay-court season that I had is emotional and that gives me calm and confidence to keep going," said Nadal.
"If you tell me seven, eight years ago that I will be here, 32 years old, having this trophy with me again, I would tell you that is something almost impossible, but here we are. I am not much worried about the future.
"If you don't have the will to improve, you don't understand the sport, because the sport is always about improving. That's the meaning of sport. It's playing with the dream of doing something better than what you're doing before.
"There is no limit. You never know where is the limit." Federer will return for the upcoming grass season and when asked about his record, Nadal said he has "no obsession" about matching and overtaking the Swiss superstar's achievements.
"I never have been crazy about all this kind of stuff," said Nadal.
"You can't be frustrated always if somebody has more money than you, if somebody has a bigger house than you, if somebody has more grand slams than you. You have to do [it] your way."