Playing his first tournament since completing his career Grand Slam at the Australian Open earlier in February, Alcaraz will next face Andrey Rublev for a spot in the final in Doha.

"It was a really close and tight match," Alcaraz said after his quarter-final win.

"I think Karen was playing great, but I knew I'd had my chances. I just didn't take them in the first set, so it was the time to keep going and try to keep fighting.

"I'm just really proud about the way that I (fought)."

The first set rumbled towards a tie-break as neither Alcaraz nor Khachanov was able to force a breakthrough on the other's serve.

Khachanov then raced into a 6-1 lead in the breaker before finally converting set-point at the third time of asking.

But seven-time Grand Slam winner Alcaraz forced his way back into the tie by breaking Khachanov to 15 in the fifth game of the second frame.

Alcaraz repeated the trick by again pouncing on the Russian's serve at 2-2 to get his nose ahead in the third set.

The world number one then broke the seventh seed in the ninth game to seal his spot in the last four in style.

There he will meet fifth seed Rublev after the Russian won his quarter-final encounter with former world number three Stefanos Tsitsipas 6-3, 7-6 (7/2).

World number two Jannik Sinner completes the last-eight line-up on Thursday when he will take on sixth seed Jakub Mensik.

The winner of that match will play Arthur Fils in the semi-finals, following the Frenchman's straight-sets victory over Jiri Lehecka.