MELBOURNE, Australia — American teenager Madison Keys advanced to the Australian Open semifinals Wednesday after overcoming a left thigh injury to beat Venus Williams, 6-3, 4-6, 6-4.

Keys received treatment on her leg after dropping serve in the second set to give Williams a 4-1 lead. After the medical timeout, the 19-year-old came back to break Williams’ serve twice to level the set at 4, but Williams then broke her next service game and served out the set.

The match featured 12 service breaks, seven won by Keys, and 83 combined unforced errors. Williams had only 10 winners to go with her 38 unforced errors; Keys had 34 winners and 45 unforced errors.

Keys will play Serena Williams in a semifinal Thursday. Serena Williams moved one step closer to her 19th Grand Slam title by beating Dominika Cibulkova 6-2, 6-2 in 65 minutes.

The No. 1-ranked Serena Williams displayed her immense power, reeling off heavy returns that included 58 winners compared to 38 from Cibulkova, last year’s runner-up.

All five previous times Serena Williams has advanced to the semifinals, she has won the title at Melbourne Park.

On Tuesday, Rafael Nadal, who had played only eight matches since last June coming into the Australian Open because of a right wrist injury and appendix surgery in early November, was knocked out in the quarterfinals 6-2, 6-0, 7-6 (5) by Tomas Berdych, who had lost 17 straight to the Spaniard.

“It is obvious that I needed something more to be more competitive,” said Nadal, a 14-time major winner. “As I said when I arrived here, the process always is not easy. When you have injuries, comebacks are difficult. But without being at my top level of tennis, I was able to be here in quarterfinals. Is not a bad result at all for me.”

Berdych, while thankful for the win, was reminded of a quote from the late Vitas Gerulaitis after beating Jimmy Connors for the first time in 16 matches: “Nobody beats Vitas Gerulaitis 17 times in a row.”

So no one, not even Nadal, could beat Berdych 18 times in a row?

“I’ve heard that one already,” Berdych said, smiling.

Berdych will play sixth-seeded Andy Murray in the semis after Murray beat local hope Nick Kyrgios, 6-3, 7-6 (5), 6-3. Kyrgios came from two sets down and saved a match point in the fourth round Sunday before beating Italian Andreas Seppi, who eliminated Roger Federer in the third round.

Kyrgios, 19, who walked onto the court with his headphones on and gave two thumbs-up to the crowd, was at his crowd-pleasing best. After hitting a backhand drop shot at the net for winner in the second set, he spread out his arms for applause and in the third set, hit a between-the-legs shot Murray easily returned.

“It was a tricky match,” Murray said. “I tried to start as quick as possible because I know how dangerous Nick is. He’s a huge hitter of the ball so I tried to keep it out of his strike zone as much as possible. Thankfully it worked.”

On the women’s side, Maria Sharapova moved closer to another Australian Open title, defeating 20-year-old Eugenie Bouchard 6-3, 6-2. The Russian made the big points look easy and advanced to play Ekaterina Makarova, who beat third-seeded Simona Halep, 6-4, 6-0.

“I felt pretty good from the start, didn’t feel that I had too many letdowns,” Sharapova said.