Seeds Petra Martic and Coco Gauff were victorious at the Emilia-Romagna Open on Wednesday, but injury cut short Sara Sorribes Tormo's run in the tournament.

Gauff recorded five breaks of serve as she overcame Italian Camila Giorgi in routine fashion, a 6-2 6-3 triumph securing the third seed a place in the quarter-finals.

The American did have a few issues on her own serve, leading to seven double faults, but ended up winning in one hour and 11 minutes.

Martic, the second seed at the event, was made to work in the first set of her match against Ludmilla Samsonova, both players saving a break point on serve as it went the distance.

There was little to split the pair in the tie-breaker too, Martic edging it 7-5 as she capitalised on her first opportunity to take the set.

The second was more straightforward for the Croatian, an early beak of serve putting her in front before she repeated the trick to wrap up victory in the ninth game.

There were wins in straight sets for fellow seeds Caroline Garcia and Wang Qiang too, as they defeated Anna-Lena Friedsam and Martina Di Giuseppe respectively.

For Garcia, the triumph means a first quarter-final appearance in the 2021 season.

Sorribes Tormo was the only seeded player to exit in the day’s action, the Spaniard forced to retire at 2-2 in the deciding set against Sara Errani due to a problem with her left thigh.

"I'm very sorry for Sara. It was a battle, I know every time we play together it is like this. I was mentally ready to fight, to suffer," Errani said in her on-court interview.

Top seed Serena Williams is already out, beaten in straight sets by Katerina Siniakova to deal the 23-time grand slam champion a further blow ahead of this year's French Open.

Serena Williams had no problems in her opening match at the Emilia-Romagna Open, but sister Venus was unable to join her in the last 16.

Top seed Serena eased to a 6-3 6-2 triumph over teenage qualifier Lisa Pigato in the highlight of Monday's action in the clay-court tournament, wrapping up the result in 68 minutes.

Pigato, 17, was making her debut in the main draw of a professional event having come through qualifying in Parma.

She enjoyed early success against the legendary Williams, too, claiming a break of serve in the opening game, but the 23-time grand slam champion soon got to grips with the task at hand.

"The first game, she played really good and I needed to adjust to get back," Serena said afterwards. "It was a bit of both, figuring out her game as well."

Next up for the American, who accepted a wildcard into the event after an early exit at the Internazionali BNL d'Italia in Rome last week, will be Katerina Siniakova, a 6-1 6-3 winner over Clara Tauson.

Venus, however, failed to make it beyond her opening outing, losing out to Anna Karolina Schmiedlova despite taking the opening set.

The Slovakian made it four wins in five meetings against the seven-time major champion, eventually prevailing 5-7 6-2 6-2 after two hours and 39 minutes on court.

Elsewhere, Sloane Stephens defeated fellow American Caty McNally in two sets, while seventh seed Sara Sorribes Tormo overcame Bernarda Pera 6-4 6-2.

There was also a win in straight sets for eighth seed Caroline Garcia, who got the better of Paula Ormaechea in a contest that saw both players serve impressively.