MELBOURNE, Australia -- Aslan Karatsev never had managed to make it into the main draw of a Grand Slam tournament. Now he just refuses to leave the Australian Open.

Karatsev, a 27-year-old Russian qualifier who is ranked 114th, became the first man in the professional era to reach the semifinals of his first major tennis tournament by beating 18th-seeded Grigor Dimitrov 2-6, 6-4, 6-1, 6-2 on Tuesday.

"It's an unbelievable feeling,'' Karatsev said. "Of course, it's first time. First time in main draw; first time semis. It's incredible.''

That's a pretty good word for what he has managed to do. Karatsev failed in nine previous attempts to go through qualifying rounds to play at a Grand Slam tournament.

Now he's making the most of it, getting past Dimitrov -- a three-time major semifinalist -- after also eliminating two other seeded players, No. 8 Diego Schwartzman and No. 20 Felix Auger-Aliassime.

"It's great to see. I think it's great to see,'' Dimitrov said about Karatsev's success. "Surprised? No.''

Bothered by back spams that developed Monday, Dimitrov was not at his best. He finished the match barely able to serve -- and barely able to walk up the stairs as he departed Rod Laver Arena.

Dimitrov jumped out to an early lead with three service breaks in the first set. He then held seven break points in Karatsev's first two service games in the second set, but didn't convert any of them.

That's when Karatsev started to believe he could stretch his already remarkable run even further.

"It was really tough in the beginning for me to hold my nerves,'' Karatsev said. "It was tricky. I tried to play in the second set, to find a way how to play."

Dimitrov stopped chasing shots in the third set, then was visited by a trainer and took a medical timeout for treatment on a muscle problem around his lower back.

He hadn't dropped a set in his first four matches here but said he had trouble putting his socks on before the match.

"It started yesterday,'' Dimitrov said, "out of the blue.''

Karatsev is the lowest-ranked man to reach the Australian Open semifinals since Patrick McEnroe -- John's brother -- also was No. 114 in 1991 -- and the lowest-ranked man to reach the semifinals at any Slam since Goran Ivanisevic was No. 125 at 2001 Wimbledon.

Karatsev will play either eight-time champion Novak Djokovic or Alexander Zverev next. Russians Daniil Medvedev and Andrey Rublev are meeting in a quarterfinal on the other half of the draw on Wednesday, meaning there'll be two Russians in the semifinals at Melbourne Park.

Asked for his thoughts on the possibility of an all-Russian final, Karatsev stuck with what he knows.

"I try not to think about it,'' he said, adding that he simply is "going from match to match.''

The Associated Press contributed to this report.