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.
“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.