Marta Kostyuk told fans at the Qatar Open to "go on YouTube" and watch her past matches with Coco Gauff after upsetting the No. 3 seed in Doha.

Gauff received a bye directly into the second round but was dumped out by the Ukrainian, who needed 72 minutes to win 6-2 7-5.

The American is now on a three-match losing streak in Doha, as she also lost her opening match last year.

Gauff has typically struggled in Doha. The 20-year-old now has a 4-4 record at the Qatar Open across four appearances.

The third seed had a tough draw, meeting world No. 21 Kostyuk in her opening match. It was a shaky performance from the American, who fired down 39 unforced errors to just eight winners.

Gauff hit back-to-back double faults to give Kostyuk match points in the final game and the Ukrainian took it on her second to advance to the last 16.

Kostyuk had never beaten Gauff on a hard court. She came into the match with a losing 1-3 record against the former US Open champion, her sole win coming on the clay in Stuttgart last year.

Kostyuk had rarely gone down without a fight in their previous meetings. Three of the 11 sets Gauff and Kostyuk had played before Monday's match had gone to tiebreaks.

But their Qatar Open affair was more one-sided, with the 22-year-old winning in straight sets. Afterwards, Kostyuk talked up their rivalry and told fans to watch one of their old contests on YouTube.

"I mean, Coco is an incredible fighter, we always have incredible matches. If you haven't seen our match in Stuttgart, go on YouTube and watch it for sure," she said.

"A great one. I just tried to stick to what I had to do and I’m very happy it worked out in two sets. Very happy to be through to round of 16."

Kostyuk will now face either Magda Linette or Magdalena Frech for a spot in the quarter-final. The world No. 21 had previously never made it past the second round in Doha.

Meanwhile, Gauff will head to Dubai for the next WTA 1000 of the season as she looks to rediscover her winning form.

The world No. 3 started the year on a high, helping America lift the United Cup and defeating Iga Swiatek en route. She then reached the quarter-final at the Australian Open, losing to Paula Badosa.

Gauff had not played since, and now finds herself on a two-match losing streak.