Hingis, a five-time grand slam winner, was something of a mentor to Federer as he emerged as a talented teenager on the men's tour - and was his teammate when the Swiss claimed his first professional victory, at the 2001 Hopman Cup.

Federer had played in an ATP Tour final prior to that event but his first individual success would only come a month after in the Milan Indoor - and Hingis has now joked that she taught Federer the winning instinct that has helped him go on to win 17 grand slam titles.

Roland-Garros men Nadal v Djokovic v Thiem: Who is the favourite for Roland Garros? 7 HOURS AGO

"You could always see the talent," Hingis said, according to the Times of India.

"I tell him I was the one who taught him how to win titles. Before that he played a few finals but didn't win anything.

"Hopman Cup was his first big title and he has won a few after that, hasn't he?"

Tennis Federer Hingis Image credit: Eurosport

Hingis was also asked about her 1998 season, during which she was just one win away from winning the calendar grand slam. Hingis won the Australian Open, Wimbledon and US Open - but lost in the final of the French Open to Iva Majoli.

Hingis never won at Roland Garros, the career grand slam eluding her.

"You know, that loss doesn't hurt me that much," she reflected.

"If I had won that French final, I might not have been hungry enough to win the Wimbledon final (against Jana Novotna). Who knows?"

ATP Hamburg Tsitsipas sweeps past Evans to advance in Hamburg 9 HOURS AGO