Dominic Thiem's demanding fitness regimen is critical to his success

Dominic Thiem's fitness regime not only makes him look fit but it plays a crucial part in his success against the big three.

The No. 4 is known as one of the fittest players on tour and has defeated each of the top three of Novak Djokovic, Rafael Nadal and Roger Federer this season. His physical shape helped him get those wins, he told Men's Journalin an interview.).

Getty Images

"It takes everything. It takes, of course, good tennis. You have to keep up with them tennis-wise, but also fitness-wise,” Thiem said. "They’re the three best players of all time, but they’re also three of probably the fittest players of all time. Always keep going. Keep momentum, no matter what’s happening. Always keep working hard and you’ll reach your goals. I try to do something everyday.”

Thiem, a two-time French Open finalist, is starting to perform better on hard courts. He reached the quarterfinals of the 2018 US Open, falling to Nadal in five tight sets, and captured his first Masters title earlier this year at Indian Wells, defeating Roger Federer in the final.

Getty Images

“I do a pretty tough program -- even twice a day. When I’m in the tournament, I reduce it a little bit," said Thiem. "My routine is very intense, but it’s normal exercises that many people probably do, too -- a lot of strength work, speed work, and a little bit of endurance with lots of core work.

“I really love to do core exercises because they don’t only make you fit, they also make you look good."

Thiem is now in New York, having delayed his arrival and spent "a lot of time in bed" since he withdrew from Cincinnati with illness. Though his illness has interfered with his training going into the US Open, the 25-year-old Thiem has kept a demanding fitness regimen during the season.

Wake up every morning with Tennis Channel Live at the US Open starting at 8 a.m. ET. For three hours leading up to the start of play, Tennis Channel's team will break down upcoming matches, review tournament storylines, breaking news and player developments.

Tennis Channel's encore, all-night match coverage will begin every evening at 11 p.m. ET, with the exception of earlier starts on Saturday and Sunday of championship weekend.