Rafael Nadal said he was not sure when he would return to tennis after his shock defeat to American Frances Tiafoe in the fourth round of the US Open on Monday. Four-time champion Nadal made his earliest exit from Flushing Meadows since 2016 following the 6-4, 4-6, 6-4, 6-3 loss to 22nd seed. Tiafoe's free-swinging performance conjured up 18 aces and 49 winners which flew past a sluggish Nadal on Arthur Ashe Stadium. For Australian and French Open champion Nadal, it was a first Grand Slam loss of 2022 after an abdominal strain forced him to <a href="https://www.thenationalnews.com/sport/tennis/2022/07/07/injured-rafael-nadal-withdraws-from-wimbledon/" target="_blank">forfeit his Wimbledon semi-final</a>. The defeat ended a run of 16 successive Grand Slams where the Spaniard had made at least the quarter-finals. "I need to go back. I need to fix things. I don't know when I'm going to come back," Nadal, 36, told a press conference. "I going to try to be ready mentally. When I feel that I will be ready to compete again, I will be there." Nadal has endured a rollercoaster year. His two major titles have taken him one clear of Novak Djokovic but his physical frailties have also returned to haunt him. The Spaniard suffered a stress fracture of the ribs in March before requiring daily pain-killing injections in his left foot to see him through to a <a href="https://www.thenationalnews.com/sport/tennis/2022/06/05/rafael-nadal-claims-14th-french-open-title-with-ruthless-victory-at-roland-garros/" target="_blank">14th French Open title in June</a>. Then his bid for a third Wimbledon crown was shattered by an abdominal injury. Nadal is due to become a father for the first time in the coming weeks, which will factor heavily into his future on-court plans. "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." Nadal is scheduled to return to action at the Laver Cup in London from September 23. He has already qualified for the ATP Tour Finals in Turin to be staged in November. Despite his 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. There is a tournament ahead if everything else goes well," he said. Tiafoe, 24, will face Andrey Rublev, whom he defeated over five sets in the third round in 2021, for a place in the semi-finals. "I don't know what to say, I'm so happy. He's one of the greatest of all time and I played unbelievable tennis today," said Tiafoe, who had only previously reached one major quarter-final in Australia in 2019. "Something special happened today. Honestly when I first came on the scene I wasn't ready for it mentally and mature enough. I've been able to develop and I have a great team around me. With you guys, it's been great." Russian seventh seed Rublev shrugged off a rain delay to breeze past Britain's Cameron Norrie and reach the quarter-finals for the third time with a 6-4, 6-4, 6-4 win. "It was two and a half hours, it was tough," said 24-year-old Rublev, who had needed four hours and five sets to get past Denis Shapovalov in the third round. "Cameron and I, we have known each other for a long time. I knew I had to give my best." Rublev, who also made the last-eight in New York in 2017 and 2020, will be playing in his sixth quarter-final at the majors but has yet to progress further. Tiafoe and Rublev are joined in the quarter-finals by Jannik Sinner after the Italian 11th seed battled past Belarus' Ilya Ivashka 6-1, 5-7, 6-2, 4-6, 6-3.