World No. 1 Caroline Wozniacki won for the first time in over a month, convincingly beating Polona Hercog in the New Haven Open, with Tuesday's play affected by an earthquake.
Wozniacki, who has never lost a match in New Haven, won 6-3, 6-0 and will face Christina McHale in the quarterfinals, a week after being beaten by the 19-year-old in their only other meeting.
In other results, Russia's Elena Vesnina beat seventh-seeded Jelena Jankovic in a first-round match that was interrupted by a distant earthquake that forced the evacuation of fans and players. Vesnina will play Spain's Anabel Media-Garrigues in the second round.
Czech Petra Cetkovska was a surprising winner over fifth-seeded Pole Agnieszka Radwanska, and third-seeded Italian Francesca Schiavone breezed past Monica Niculescu of Romania 6-1, 6-2.
McHale, the only American in the draw, needed just 1 hour and 11 minutes to beat Carla Suarez Navarro of Spain 6-2, 6-2.
McHale said she doesn't view herself as a favourite against Wozniacki, despite her previous success.
"She's the No. 1 player," she said. "She's a very good player and I'm not going to be any more confident because I beat her once."
Wozniacki, who lost in her first matches at both Toronto and Cincinnati, had an easier time Tuesday. Playing with her boyfriend, US Open golf champion Rory McIlroy, watching from the stands, the Dane broke Hercog to go up 5-3 in the first set and didn't lose another game.
"I'm definitely a player who likes to play matches and always plays better when I've gotten a few matches under my belt," she said. "So it definitely is nice that I could come back here and win my first match."
Vesnina upset Jankovic 6-4, 2-6, 6-4. Vesnina was leading 2-0 in the first set when the quake - which was centered in Virginia - sent the Connecticut Tennis Center swaying, forced the evacuation of the stadium and caused a delay of over two hours.
The magnitude-5.8 quake was felt all along the East Coast of the United States.
After play resumed, Vesnina held on to win the set, but she dropped the second and was tied at 4-4 in the third before breaking seventh-seeded Jankovic's serve in the final game of the match.
"I will remember this day for the rest of my life," Vesnina said. "There is nothing you can say. It's just like you won the match after the earthquake and it just feels great."
Jankovic arrived at the tournament on Monday after playing in the finals of last week's tournament in Cincinnati.
She said she felt flat and tired, especially after waiting for two hours in the grass outside the stadium while it was being cleared by the fire marshal and building inspectors.
"It doesn't make you feel good before going on the court," she said. "It's not like you are sitting on a couch. You are just sitting in the middle of nowhere and mosquitoes biting you and bugs and spiders crawling over you."
Radwanska lost to Cetkovska 6-4, 5-7, 6-3.
Cetkovska was leading 3-1 in the second set before Radwanska fought back to level the match, but was able to regain the momentum in the third set, breaking Radwanska in the final game.
"It was pretty difficult in my head to keep going because I was pretty tired and a little bit frustrated with myself," Cetkovska said. "But I kept fighting and I was trying to do what was working in the first set."