Roger Federer will not be losing any sleep over whether rival Rafa Nadal can match his men's record 20 Grand Slam singles titles, according to his long-term coach Severin Luthi.
The 38-year-old Swiss began the year three ahead of second-placed Nadal's haul but the Spaniard claimed a 12th French Open title this year followed up by winning the U.S. Open this month.
It has re-energised the GOAT (greatest of all time) debate with Nadal, who has 19 slams, looking back to his best after injury concerns earlier this year.
Never in his career has Nadal been only one Grand Slam title behind Federer, who squandered two match points against Novak Djokovic in this year's Wimbledon final.
"No, I don't think he stresses (about Nadal catching him up)," Swiss Luthi, who has toured with Federer since 2007, told Reuters in an interview.