Russian advances in straight sets to book a meeting with French Open champion Ostapenko.
Kasatkina, Makarova, Vesnina and Osaka reach second round: WTA Dubai Duty Free Tennis Championships Day 1 updates
Daria Kasatkina knocked out 2012 champion Agnieszka Radwanska in the first round of the Dubai Duty Free Tennis Championships on Monday.
Kasatkina, the world No 24 from Russia, claimed a 7-5, 6-4 victory in one hour and 57 minutes to set up a second round meeting with either Britain's Johanna Konta or compatriot Anastasia Pavlyuchenkova.
Kasatkina, 20, was the aggressor throughout the match and she got her reward in the fifth game to break for a 3-2 lead. Radwanska soon got back on level terms at 4-4, but immediately handed the initiative back to Kasatkina, who in turn was broken back for 5-5.
However, Radwanska was unable to nudge ahead, and despite leading 40-15 on serve, was broken once again as Kasatkina served out the opening set.
Both players continued to struggle on serve in the second set. Kasatkina raced into a 3-0 lead after twice breaking Radwanska, only for the world No 31 from Poland to emulate her opponent to level the set at 3-3. Once again, Radwanska failed to take the lead, with Kasatkina breaking back before the Russian surrendered her serve at 4-4.
Radwanska was then broken again for 5-4 as Kasatkina held her nerve to serve out the match.
Osaka races past Mladenovic
Japan's Naomi Osaka produced a dominant performance in the first round of the Dubai Duty Free Tennis Championships on Monday to defeat France's Kristina Mladenovic.
Osaka, 20, needed just 71 minutes to defeat world No 14 Mladenovic 6-2, 6-2 to set up a second round meeting with the winner of Samantha Stosur's match against Anett Kontaveit.
Osaka asserted her dominance immediately by breaking Mladenovic to love in the Frenchwoman's first service game before storming in to a 5-1 lead with a second service break.
Despite a wobble when serving for the set, Osaka broke Mladenovic for a third time to seal the opener.
Osaka, the world No 48, started the second set in similar fashion to the first, breaking Mladenovic immediately, and although she surrendered her advantage, another service break handed the Japanese player a 3-1 lead.
Mladenovic was broken for the final time when trailing 5-2 as Osaka sealed a comfortable win.
Makarova battles back from brink to reach second round
Ekaterina Makarova fought back against Anastasija Sevastova to book her place in the second round of the Dubai Duty Free Tennis Championships.
Makarova, the world No 37 from Russia, dropped the first set 6-3, was down a break in the second set, and faced match point before emerging victorious 3-6, 7-6, 6-3 in two hours and 28 minutes.
It was a remarkable turnaround from Makarova in the face of some big serving from world No 16 Sevastova, who hammered down 14 aces during the match.
Makarova will face either France's world No 7 Caroline Garcia or the world No 30 from Czech Republic Lucie Safarova in the second round.
Vesnina sets up Ostapenko clash
Elena Vesnina defeated Shuai Peng 6-4, 7-5 in the opening match of the WTA Dubai Duty Free Tennis Championships to book a second round showdown with French Open champion Jelena Ostapenko.
In the 11th meeting between the players, Russia's Vesnina registered her fifth win against China's top-ranked woman in one hour, 43 minutes.
Vesnina, 31, got off to the ideal start, breaking Peng in the first game before streaking in to a 4-1 lead. The momentum then swung the way of Peng, who fought back to level the set at 4-4, only for Vesnina to earn a second break when leading 5-4 to claim the opening set.
Peng started the second set in style by breaking the Vesnina serve, but her advantage lasted just two games. The rest of the second set stayed on serve until Peng wavered when serving at 5-6 as Vesnina converted her first match point.
Vesnina will now look to make it two wins from two against Ostapenko having beaten the world No 6 from Latvia in their only previous meeting at the 2016 Madrid Open.