MELBOURNE, Feb 14 (Reuters) - Russian qualifier Aslan Karatsev continued his fairytale run at the Australian Open on Sunday, reaching the quarter-finals on his Grand Slam debut with a 3-6 1-6 6-3 6-3 6-4 win over 20th seed Felix Auger-Aliassime
Canadian Auger-Aliassime looked headed for a comfortable victory at Margaret Court Arena as he raced into a 2-0 lead, but with nothing to lose the 27-year-old Russian went for broke and rallied to victory.
"It was really difficult in the beginning to play with him. He's a really good player and was playing really fast and it took me two sets to find my rhythm," Karatsev, ranked 114th in the world, said in his on-court interview.
"I put everything into this match and I'm really happy."
Playing the first five-setters of their careers, both players showed nerves but it was Karatsev who displayed better control in the end as the unforced errors mounted for the 20-year-old Auger-Aliassime.
Karatsev converted his first match point with a forehand crosscourt winner and celebrated with a huge roar as he became the first male player since Alex Radulescu at Wimbledon in 1996 to reach a Grand Slam quarter-final on their debut.
Karatsev also became the lowest-ranked man to reach the Australian Open quarters since No. 114 Patrick McEnroe in 1991.
He will next play either third seed Dominic Thiem of Austria or Bulgarian Grigor Dimitrov, seeded 18th, for a place in the semi-finals at Melbourne Park.
"I'll be ready for everyone," said Karatsev, one of three Russians who reached the last 16 this year. Daniil Medvedev and Andrey Rublev will be in action on Monday.