Aryna Sabalenka, Danielle Collins to square off in Rome semifinals

Any worries about Aryna Sabalenka's ailing lower back were put to rest Wednesday when the World No. 2 defeated Jelena Ostapenko 6-2, 6-4 in an efficient 72 minutes to move into the semifinals of the Internazionali BNL d'Italia in Rome.

"I was testing my body on the warmup and I felt, 'OK, I'm probably going to go on the court and play,'" she told reporters of the injury she suffered in her most recent match against Elina Svitolina. "And I'm super happy I was able to play without pain today. Hopefully, with every day I will feel better and better.

"I would definitely say that was the best performance of the tournament."

Sabalenka, from Belarus, controlled the match. She won 81 percent of her first serves, didn't face a break point and converted three of her seven break chances. Sabalenka had 12 winners and 11 unforced errors; Ostapenko had 18 of each.

Latvia's Ostapenko, the ninth seed, was seeking her second consecutive semifinals berth in Rome. She now is 7-4 in the quarterfinals of WTA 1000 events.

Ostapenko won the opening game of the match, but Sabalenka rattled off five straight victories breaking Ostapenko twice in deuce games in the stretch.

Sabalenka also broke her opponent's serve in the seventh game of the second set to go up 4-3 en route to the win.

In the semifinals, Sabalenka will face No. 13 seed Danielle Collins, who defeated No. 24 Victoria Azarenka of Belarus 6-4, 6-3 on Wednesday.

Sabalenka beat Collins in three sets in the fourth round at the Mutua Madrid Open on April 29.

It was a rare defeat for Collins on the season, who has won 19 of her past 20 matches, earning titles at the Miami Open and the Charleston Open. Earlier this year, Collins announced this would be her final season on tour.

The other semifinal will pit top seed Iga Swiatek of Poland against third-seeded Coco Gauff on Thursday. Collins and Gauff will be the first two American women to compete in the semifinal round in Rome since 2016, when Serena Williams and Madison Keys accomplished the feat.