Elena Rybakina came from a set down to stun Australian Open champion Sofia Kenin and reach the second round of the Dubai Duty Free Tennis Championships.

The 20 year-old battled back to defeat the world No 7 6-7 (2) 6-3 6-3 in a gruelling contest that lasted more than two hours.

Coming off the back of her first Grand Slam victory, Kenin was beaten by Jelena Ostapenko in the Fed Cup last week, but started with a vengeance in Dubai as she broke Rybakina in the opening game.

The pair then held their serves until Kenin stepped up to serve for the first set, only to lose the game as the Kazakh-Russian forced a tie-break.

But the American, buoyed by her success in Melbourne, played a superb seven points to ease the tie-break as she put herself on the way to round two.

The second set remained a tight affair, before Rybakina began to get on top as she broke twice to win four games in a row and send the match to a decider.

And in a final set with very few break point opportunities, it was the underdog who prevailed as she broke at 4-3 and closed out the match to cause a big upset.

Speaking after the match, Rybakina said: "I've worked a lot, and it's amazing that I managed to win today. I just finished a tournament, and I only came here one day before [this match], so I'm happy. I'm so happy with my win today. I think today I followed my tactics, and that was the key to win."

"I didn't nervous at all because I knew it's going to be tough. Actually, I prepared myself like it's a good practice. I didn't expect that I will win. I mean, I tried to do my best, but I was not nervous.

"Of course I believed. I didn't think that she just won Australian Open because I know that now everyone could beat everyone. I didn't think about this."

Meanwhile, Kenin was not happy with her performance as she lamented the match slipping away from her.

"I just didn't feel my game really well," she said.

"Of course, she played well. I just made too many unforced errors. I just didn't take my chances. I felt really off the whole match. I tried to somehow get back in there, hang in there, but it just didn't work out today.

"I really thought I could have somehow turned it around. I felt like I had the match play, I had the confidence. It just didn't work out today. It's obviously really upsetting and disappointing at the moment.

"I just got to prepare for doubles [with Bethanie Mattek-Sands] for tomorrow. Hopefully, we can get the win. Next is Doha for me. I will try to do my best. There's a lot more tournaments coming up...hopefully, I can play better there. Hopefully, I can bring my game up there."