Roger Federer is coming towards the latter end of his career and is expected to soon hang up his racket for good, a report claimed.
However, the 37-year-old Swiss star signed a 10-year deal with Uniqlo earlier this year prompting many to think he will play until at least the 2020 Olympics in Tokyo.
But Luthi has predicted Federer will retire between 2019 and 2021 – meaning he will not play beyond 40 years old.
“I do not like to speak a lot about his retirement and he does not like to talk about it, because it’s like it approaches faster,” Luthi told Le Temps.
“I can see him playing for at least one to three years more.
“For the Davis Cup, it’s different, my contract ends at the end of 2018.
“I want to think about what I want for me.”
Federer is constantly quizzed on when he will call time on his illustrious career.
But the 20-time Grand Slam winner always gives the same response – when his body tells him he is ready.
Federer wants to continue battling at the top of the sport, especially as his records are under threat by the younger Rafael Nadal and Novak Djokovic.
However, the world No 3 is unsure if he will play in the France ever again after losing to Djokovic in the Paris Masters semi-final yesterday – another clue that his career is nearer the end than many imagine.
“No idea if it was the last match (in Paris),” he said.
“As I said for the French Open, I will decide at the end of the year to see how it will have an impact on my physical training.
“Bercy (Paris Masters) as for next year, it’s like every year, it’s always difficult.”