Former champion Andy Murray produced an astonishing fightback to outlast Japan's Yoshihito Nishioka 4-6, 4-6, 7-6, 7-6, 6-4 in his long-awaited return to Grand Slam singles action in the US Open first round.The 33-year-old Briton, contesting a singles match at a major for the first since the 2019 Australian Open, appeared to be heading for an early exit as a fearless Nishioka outplayed him for two sets at the Arthur Ashe Stadium. Yet, as he has so often done throughout his career, Murray simply refused to accept defeat.Desperately trying to spark himself into life, Murray recovered from a break down in the third set and saved a match point late in the fourth.At the start of the fifth set he required treatment on his battered toes and again slipped a break behind before dredging his tank to finally crush 49th-ranked Nishioka's spirit and claim victory in four hours 38 minutes.It was Murray's 10th win from two sets down and showed that despite undergoing two hip surgeries, he remains one of the sport's great warriors. Murray will have to recover quickly as his next opponent could be Canadian 15th seed Felix Auger-Aliassime. He said his first job was to try and find an ice bath. Murray, who claimed the first of his three Grand Slam titles in New York in 2012, opened the match with a delicious topspin lob, but for the next two sets was second best against the 24-year-old showing absolutely no respect for reputations. Nishioka broke decisively at 3-3 in the opener and sprinted 4-0 ahead in the second as Murray briefly looked ready to fold.Murray was a point away from falling 5-0 behind but clawed his way back only to break a string and balloon a forehand long on set point when returning at 4-5 down.Nishioka led 3-1 in the third set but with his back to the wall Murray ratcheted up the power on his forehand and broke back. Murray saved more break points at 5-5 but eventually wrestled the set from Nishioka in the tiebreak.