New York, Aug 30 (IANS): Colombian qualifier Daniel Elahi Galan caused a major upset at the US Open on Tuesday, showing fourth-seeded Stefanos Tsitsipas the exit door with a hard-fought 6-0, 6-1, 3-6, 7-5 victory against the Greek player on Tuesday.

With the help of 41 winners, the world No. 94 reached the second round at Flushing Meadows after a two hours and 48 minutes slugfest on his main draw debut at the season's final major.

This was the 26-year-old Colombian's biggest win of his career.

"Definitely one of the best moments of my career," Galan was quoted as saying by atptour.com. "Definitely the best match of my career, not only because of the circumstances, also the opponent. I'm really happy."

Galan, who did not lose a set in qualifying, won the first 11 games of the match against Tsitsipas with a superb display of aggression.

"I think he (Tsitsipas) started playing better in the third set. He served much better than the first two and I was putting the serve in the court, but not putting pressure on him. He was always in control," Galan said.

"I think he felt really comfortable during those two sets. I tried to change a little bit the position when I was returning and that changed a lot because I was able to return (deeper) and he was not so offensive on the first ball, so I was able to do a little bit more."

Galan had entered the match with a 0-6 record against Top-20 opponents. He had reached the third round at Wimbledon and his confidence showed against Tsitsipas. The Greek has now lost in the first round of the US Open in two of his five appearances and has never advanced to the second week. He made 57 unforced errors compared to 28 winners in his defeat, according to atptour.com.

"He dominated the match," Tsitsipas admitted. "I just couldn't get into it."