The Spanish champion was knocked out of the US Open at the hands of Frances Tiafoe on Monday, ending his undefeated streak at grand slams this year at 22 matches.
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A four-time champion in New York and bidding for a 23rd grand slam title, Nadal lost 6-4, 4-6, 6-4, 6-3 to Tiafoe in the quarter-finals.
Speaking to reporters in his post-match press conference, Nadal made the sad admission that he doesn't know when he will be back on court.
The 36-year-old said he needed to return home to Spain to be with pregnant wife Xisca, who was recently hospitalised in Mallorca.
"I need to go back. I need to fix things. I don't know when I'm going to come back," he said.
"I going to try to be ready mentally. When I feel that I will be ready to compete again, I will be there."
Nadal is due to become a father for the first time in the coming weeks, a factor which will factor heavily into his future on-court plans.
The 36-year-old was reportedly left fuming last week when footage of Xisca being admitted to hospital was leaked on social media.
"Now I have to go home, I have more important things than tennis to attend to," he said.
"Decisions will be made based on how everything goes in my personal life, which comes before my professional life.
"It's been a bit difficult for a few months but I want to finish the year with something very important that is my first child."
The 22-time grand slam champion has previously stated that he didn't want to start a family until after his career has ended.
Rafa Nadal not ruling out playing again in 2022
Discussing his comments on Channel 9, Aussie greats Jelena Dokic and Todd Woodbridge said they didn't think Nadal would be back playing until the Australian Open in January.
Despite doubts over his future plans, Nadal told Spanish media that he won't rule out playing again this year.
"I will do a mini pre-season to finish the year in Europe with good feelings, and that is what we are going to try," he said.
"There is a tournament ahead if everything else goes well."
The Spaniard is due to play in the Laver Cup alongside Roger Federer, Novak Djokovic and Andy Murray from September 23-26.
If Nadal is available, it would mark the first time that all four members of the 'Big 4' play together on the same team.
Discussing his loss to Tiafoe, Nadal admitted that age caught up to him against his 26-year-old opponent.
"I was not able to push him back. Tennis is a sport of position a lot of times," he said.
"If not, you need to be very, very quick and very young. I am not in that moment anymore."
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