The eleventh-ranked Hurkacz won with 6-3,3-6,7-6(8-6).
The two points that separated the tiebreak were also what separated the players throughout the match.
Hurkacz won 112 points against 69-ranked Ymer's 110.
The match ball was perhaps the best of the match.
The ball went over the net 16 times, where Ymer had the upper hand several times but Hurkacz was able to counter and win after Ymer hit the net in the 17th shot of the duel.
The Pole cheered as if he had won the entire tournament afterwards and threw the racket in a frenzy.
Murray saved five match points in Doha
In Dubai, the 35-year-old Scotsman Andy Murray reached the final after saving five match points against Jiri Lehecka.
The numbers were written as 6-0,3-6,7-6(8-6).
- I don't know how I won this match.
It's one of the most amazing turnarounds I've had in my entire career, says Murray to the ATP website.