Ariya Jutanugarn

Ariya Jutanugarn of Thailand smiles after she and her sister Moriya defeated Taiwan during round two of the International Crown at Caves Valley Golf Club. (Rob Carr, Getty Images / July 25, 2014)

Thailand's Ariya and Moriya Jutanugarn grew up playing with and competing against each other. The sisters' rivalry dates back to their days as amateurs and continues in their professional careers.

Even when the two are paired together in match play, competition with each other is what drives them.

"Before I tee off," Ariya said, "I say, 'I'm going to make birdie.' And she says …"

Here, Moriya interrupts: "No, I'm going to make birdie."

The drive to be better served the Jutanugarn sisters well on day two of the inaugural International Crown at Caves Valley Golf Club. The twosome beat Candie Kung and Teresa Lu of Taiwan on Friday, 3 and 2, for Thailand's first victory of the tournament.

Ariya and Moriya Jutanugarn were also paired together Thursday, when they halved with Spain's Belen Mozo and Beatriz Recari. Ariya struggled mightily throughout the day, especially on her drives. Moriya said it was partly due to nerves.

On Friday, both sisters opened with birdies on the par-4 first for a 1-up advantage. Ariya made par on No. 6 to push the lead to 2-up, and both sisters birdied again on No. 11 to push their lead to 3-up.

"I just tried to keep her more calm [today]," Moriya said. "We were kind of joking around, just like that, and she kept me calm, too."

Thailand ended the second day of competition with two victories that earned them four points. Their total of five points is good for first place in Pool A.

The United States — who will play Thailand on Saturday, the last day of pool play — is tied with Taiwan for second place with four points, while Spain sits in fourth with three points.

Thailand's second victory wasn't decided until Onnarin Sattayabanphot sank a 17-foot birdie putt on No. 18 for a 1-up victory with Pornanong Phatlum over Taiwan's Yani Tseng and Phoebe Yao.

"That putt, that gave me goose bumps," Sattayabanphot said. "It was all I had today. I'm really glad it went in."

Australia pair blows 6-stroke lead

Katherine Kirk and Lindsey Wright each had a chance to stop Australia's nose dive with one last putt on the day.

The pair squandered a 6-up advantage it had gained through the first 11 holes Friday against Japan's Ai Miyazato and Sakura Yokomine. But going into No. 18, Australia was just 1-up.

Miyazato and Yokomine each shot par on the par-4 18th. One par from either Kirk or Wright would have given seventh-seeded Australia the two points that come with a match victory.

Both Kirk and Wright missed their last putts of the day. They halved the match with Miyazato and Yokomine to earn one point for Australia.

"It hurts, obviously, but we can't change what's happened," Kirk said. "We can learn from it and certainly go out there tomorrow and try and make amends."

After a birdie from Wright on No. 11 put her pairing 6-up, Australia needed to win the next hole or finish the next two all square in order to shut the door early on Japan with a 6-up win.

A birdie from Yokomine on the 12th hole got things started for Japan while Australia faltered down the stretch. Kirk and Wright each bogeyed hole No. 13 and double-boyed No. 14 before bogeys on the 18th hole.