US Open title defense in doubt for Dominic Thiem

Dominic Thiem is still "several weeks" away from knowing when he will get back on tour, says coach Nicolas Massu—prompting questions about whether he will get to defend his title at the US Open.

The 27-year-old Austrian has already withdrawn from Cincinnati and Toronto, still sidelined with the tendon-sheath tear in his right wrist which he experienced on court in Mallorca. The injury forced him to withdraw from Wimbledon, and he is also not playing the Olympics this week, which Massu won at the 2004 Sumemr Games in Athens.

That layoff is now looking as if it will be a lot longer. Thiem posed a video of himself a week ago hitting with his left hand, saying he was "finally back on court" but still with strapping on his right hand.

WATCH: An acute injury in Mallorca forced Thiem out of competing at this year's Wimbledon Championships.

"The wrist is an area that to return to competition has to be perfect," Massu told Punto de Break in Spanish. "Whenever that is, do it 100 percent so it does not become chronic."

The coach said it would still be "several weeks before we know exactly when he will be able to return."

Thiem, who won his first Grand Slam title at the 2020 US Open, has been up and down this season, winning nine rounds in nine events and exiting in the first round of Roland Garros before his injury in Mallorca. Having reached a career-high of No. 3 in 2020, he is now No. 6 in the rankings.

Thiem has also reached three other Grand Slam finals in his career so far, one at the Australian Open and two at the French Open.