Thiem could have closed things more than an hour earlier, but he frittered away four match points in the second-set tiebreaker, including one by double-faulting.
Then the U.S. Open champion trailed 4-0 in the last tiebreaker before turning things around. When it ended with Djokovic sailing a forehand long, Thiem dropped his racket and covered his face with his hands.
”It was, for sure, a mental battle,” Thiem said.
The No. 3-ranked Thiem’s 300th career match win put him in the final of the season-ending tournament for the second straight year; he was runner-up to Stefanos Tsitsipas in 2019.
No. 2 Rafael Nadal was scheduled to face No. 4 Daniil Medvedev in Saturday’s second semifinal. The final is Sunday. None of the last three men in…