Rafael Nadal will play again when he's "ready mentally"; Djokovic withdraws from Davis Cup tie next week

How it Happened: Annacone and Rubin break down Tiafoe's big win over Nadal

It's not apparent when Rafael Nadal and Novak Djokovic will next be on a tennis court, with uncertainty surrounding their schedules for the next few weeks.

The 36-year-old from Spain, who lost to Frances Tiafoe in the fourth round of the US Open on Monday, had played just one warmup event as he recovered from the abdominal injury that forced his withdrawal from the Wimbledon semifinals.

Despite his lack of preparation, Nadal said his level of play had been good in practice but alluded to personal challenges in recent months. His wife, Maria Francisca, is expecting their first child, and unconfirmed rumors of minor complications had surfaced prior to Flushing Meadows.

"But then when the competition start, my level went down," said Nadal, adding, "I don't know, mental issues in terms of a lot of things happened."

Nadal said he was now going home to "fix things," and indicated he was not sure whether he would appear at Laver Cup as scheduled in three weeks. The baby is due next month.

"I don't know when I going to come back. I going to try to be ready mentally. When I feel that I will be ready to compete again, I will be there," he said.

Djokovic, whose vaccination status kept him from playing the US Open, has withdrawn from next week's Davis Cup group tie next week.

"Nole will not play for personal reasons," Serbia's Davis Cup captain told local press, adding that he still planned to play the Davis Cup Finals if Serbia qualifies next week.

Djokovic is also on on Laver Cup's European team. In addition, the 35-year-old Serbian was also recently added to the lineup for the ATP event in Tel Aviv.