Top seed Sofia Kenin made a winning start to her season as she beat qualifier Yang Zhaoxuan at the Abu Dhabi Open.
The world No 4 needed over an hour to take the opening set but eventually advanced with a 7-6(4), 6-2 victory.
"It was the first match, obviously a bit of nerves, I had to find my groove," said Kenin, who will be defending her Australian Open title in Melbourne next month.
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“Conditions weren't easy, it was quite windy. The first set was tough for me. I couldn't find the ball, I guess. But the second set I started off strong."
Garbine Muguruza also made it through to the second round as she beat Kristina Mladenovic 6-2, 6-4.
Fifth seed Muguruza was helped by 11 double faults from Mladenovic, including five in the final game of the match.
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"I was trying to do my game, dominating, not letting her dominate the point," said Muguruza. "It’s the first match of the year, it’s a little bit tricky to get the feeling, but I’m happy with the win."
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Karolina Pliskova won 6-2, 7-6(4) against lucky loser Despina Papamichail, who came in as a replacement for the injured Sorana Cirstea.
Heather Watson fought back from a set and a break down to beat fellow Brit Jodie Burrage 4-6, 6-2, 7-5 in two hours and 22 minutes.
Second seed Elina Svitolina beat Jessica Pegula 6-4, 6-3, fourth seed Aryna Sabalenka overcame Polona Hercog 7-6(5), 6-2 while 16-year-old Coco Gauff breezed through with a 6-0, 6-1 thrashing of Ulrikke Eikeri.
World No 87 Tamara Zidanesek caused an upset as she battled back to beat 11th seed Jennifer Brady after failing to win a game in the first set.
Zidanesek won 0-6, 6-3, 6-4 to advance to the second round.
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