Novak Djokovic has commended the “bravery” of Aslan Karatsev and his “excellent play in the important moments”.
But the Tennis World number one also revealed that he actually felt “dizzy” in the third set.
Karatsev rose from 114th to inside the top 50 following his improbable run as a qualifier at the Australian Open as Djokovic won the tournament for a record ninth time.
“You have to put (in) like 200 per cent to beat this guy, it’s like playing against a wall,” said Karatsev.
“This is definitely (the biggest win of my career), it’s the World No 1,” he added.
“I’m really happy, I put everything on the court. The match was long. I’m really happy with my performance today.”
Djokovic, the 2009 and 2011 champion surrendered a 3-0 advantage in the opening set as he dropped serve three times.
The Serb then fell 4-2 behind in the second. But he summoned his well-documented powers of recovery to win four straight games and send the match to a deciding set.
Dubai champion, Karatsev fended off eight break points in the third set.
That was before winning Djokovic’s service game to move 4-3 ahead and leave the top seed on the brink.
Djokovic saved a match point down 5-3 to force Karatsev to serve it out.
The third seed saved two further breakpoints as he completed a landmark win after three hours and 25 minutes.
Karatsev will face 10th-ranked Matteo Berrettini in Sunday’s final after he overcame Japan’s world number 126 Taro Daniel.