Novak Djokovic beats Learner Tien 6-1, 7-6 (7-3), 6-2 in two hours and 24 minutes
To face another American opponent in Zachary Svajda in second round
Daniil Medvedev goes down 3-6, 5-7, 7-6 (7-5), 6-0, 4-6 to Benjamin Bonzi
Novak Djokovic overcame more fitness issues as he defeated Learner Tien in the first round of the US Open.
The 38-year-old won 6-1 7-6 (7-3) 6-2 in two hours and 24 minutes to set up a second-round match against another American opponent in Zachary Svajda.
Djokovic was off to a flying start, dropping just five points in the opening three games before securing the first set in just 25 minutes.
Tien fought back well in the second, where Djokovic made 20 unforced errors as he struggled physically, but the teenager failed to convert a set point in the 10th game as the Serb forced a tiebreak.
Djokovic won the tiebreak, winning points on all five of Tien’s serves, before taking that momentum into the third set and clinching the win with his second match point.
Meanwhile, 2021 US Open champion Daniil Medvedev suffered another first-round exit in grand slams this year after losing in five sets to Benjamin Bonzi.
Bonzi, who also knocked Medvedev out in the first round at Wimbledon this year, won 6-3 7-5 6-7 (5-7) 0-6 6-4 after surviving a fighting display against the former world number one.
Medvedev looked to have all the momentum heading into the deciding set, dropping just nine points in the fourth, but Bonzi held five break points in the seventh game before securing the win in the 10th with a break of serve.
Data Debrief: Consistency for Djokovic, anguish for Medvedev
Following his win over Tien, Djokovic has now claimed a 75th consecutive first-round win at grand slams.
He is the first player (male or female) to achieve this in singles main draws in the Open Era, with 55 of those victories coming in straight sets.
Medvedev, on the other hand, has claimed just one win in grand slams this year after first-round exits at the French Open, Wimbledon and the US Open.
With victories over Medvedev at Wimbledon and the US Open, Bonzi has become the first player in the Open Era to defeat a grand slam champion in opening men's singles matches at consecutive grand slam events.
