WIMBLEDON, England >> Ash Barty played her first match as the No. 1 player in the world on No. 1 Court at Wimbledon, and she won.

The top-seeded Australian, who followed her victory at the French Open by winning a grass-court warm-up tournament in Birmingham, advanced to the second round at the All England Club today by winning her 13th straight match. She beat Zheng Saisai 6-4, 6-2.

“It feels incredible,” Barty said about playing at Wimbledon as the top-ranked woman. “It’s a little bit of a bizarre feeling, to be honest. But I just try and go about my business the exact same way.

“This hallowed turf that we do get to play on is sacred, it’s beautiful. And you have to enjoy every minute.”

Defending champion Angelique Kerber also advanced, beating Tatjana Maria 6-4, 6-3 on Centre Court.

“I was really nervous, to be honest, because of course to (go) out there as the defending champion, it was really special,” Kerber said. “Walking on the Centre Court, playing there again, I mean, a lot of emotions, a lot of memories.”

Both Barty and Kerber are in the same quarter of the women’s draw, which means they could meet in the quarterfinals. Seven-time champion Serena Williams is also in that same quarter, and she also won, beating Giulia Gatto-Monticone of Italy 6-2, 7-5.

Garbine Muguruza, the 2017 Wimbledon champion who was also placed in that same tough quarter of the draw, didn’t make it through her first match. And neither did Maria Sharapova, the champion in 2004.

Muguruza, seeded 26th, lost to Brazilian qualifier Beatriz Haddad Maia 6-4, 6-4. Sharapova, who served for the match while leading 5-3 in the second, retired from her match with a left wrist injury while trailing Pauline Parmentier of France 4-6, 7-6 (4), 5-0.

The combative and combustible Nick Kyrgios advanced to the second round despite winning only five points in the fourth set. The unseeded Australian beat Jordan Thompson 7-6 (4), 3-6, 7-6 (10), 0-6, 6-1.

Kyrgios took a medical timeout after the second set and a trainer came on court to examine his left side. He then won the third set in a tiebreaker — a set which took 1 hour, 16 minutes to complete.

The fourth set, however, lasted only 18 minutes as Thompson won 24 points while Kyrgios took only five.

“The medical timeout was to loosen up my hamstring a little bit. It was a physical match.” Kyrgios said. “Especially on the grass, it was a little bit slower this year. There were a lot more rallies.”

Kyrgios will face two-time champion Rafael Nadal in the next round. The Spaniard beat Yuichi Sugita of Japan 6-3, 6-1, 6-3.

Eight-time champion Roger Federer lost the opening set of his opening match on Centre Court, but he quickly recovered and beat Lloyd Harris of South Africa 3-6, 6-1, 6-2, 6-2.

Federer, who is seeded second at the All England Club, reached the second round at Wimbledon for the 17th consecutive year.

However, fifth-seeded Dominic Thiem, who lost to Nadal in the French Open final, was eliminated after losing to Sam Querrey 6-7 (4), 7-6 (1), 6-3, 6-0.

Thiem follows a pair of other top seeds out of the tournament in the first round. No. 6 Alexander Zverev and No. 7 Stefanos Tsitsipas lost on Monday.

“I was mentally prepared for this kind of game,” said Thiem, who has had much more success on the slower clay surface. “Just broke down a little bit after he converted his first break chance, and that was it basically.”