ROME — World No. 5 Alexander Zverev continued his poor recent form as he crashed out of the Italian Open in the second round after a 7-5, 7-5 defeat by home favorite Matteo Berrettini on Tuesday.

In first-round action, David Goffin produced two blistering sets to fight back and beat Stanislav Wawrinka 4-6, 6-0, 6-2, while Nick Kyrgios treated the crowd to an array of his antics in a 6-3, 3-6, 6-3, victory over Russian Daniil Medvedev.

In the women's draw, Serena Williams was forced to pull out due to a persistent knee injury, throwing into doubt her participation in the French Open which begins this month.

Roared on by a partisan home crowd at the Foro Italico, Berrettini took the opening three games against Zverev, before the 2017 champion and last year's runner-up regained his composure.

Berrettini then saved five break points to take a 6-5 lead before the rattled Zverev, who beat the Italian in the same round last year, threw away the opening set with two unforced errors and a double fault.

They traded breaks early in the second before Zverev, who saved a match point in the 10th game, committed another flurry of errors, capped by a forehand into the net to hand Berrettini a memorable win.

Zverev has not gone past the quarterfinal at any tournament since reaching the Acapulco final in early March.

The flamboyant and unpredictable Kyrgios again treated the fans to his best and worst as he combined spectacular shots with some poor behavior.

The Australian won the opening point of the match with what is fast becoming a trademark underarm serve and breezed through the first set before cheers from the crowd turned to jeers amid a second-set meltdown.

Having dropped serve to hand Medvedev a 5-3 lead, Kyrgios blasted a ball over the stands, turned his back to Medvedev and exchanged words with the umpire before the Russian held to force a third set.

As if nothing had happened, Kyrgios got back to business as he hammered aces and winners, having also capped some good forays to the net with confident volleys to book a second-round clash with Norwegian Casper Ruud.

Goffin dropped the opening set against Wawrinka before he blew away the Swiss in the next two, the decisive moment coming in the second game of the third when the Belgian saved a double break point at 1-0 down.

He won the next five games and although Wawrinka briefly delayed the inevitable, Goffin was able to celebrate after his frustrated opponent blazed a forehand into the crowd.

In the women's tournament, holder Elina Svitolina was leading Victoria Azarenka 6-4, 1-4 in an evening encounter before rain suspended play.

Kristina Mladenovic cruised past French compatriot Caroline Garcia 6-1, 6-2 while Ashleigh Barty had to work hard for a 4-6, 6-3, 6-4, win over Viktoria Kuzmova.

The top men get their campaigns underway on Wednesday when world number one Novak Djokovic, fresh from winning last week's Madrid Open, takes on Canadian Denis Shapovalov.

Meanwhile, Serena, the 37-year-old American world No. 11, had been due to face sister Venus in an eagerly-awaited second-round clash in Rome. Venus received a walkover into the third round.

Serena, a 23-times Grand Slam singles champion, has struggled with injuries since reaching the quarter-finals of this year's Australian Open, although she had breezed through her opening match against Swede Rebecca Peterson.

"I must withdraw from the Italian Open due to pain in my left knee," the four-times Rome champion said. "I will miss the fans and competition at one of my favorite tournaments.

"I'll be concentrating on rehab and look forward to seeing you all at the French Open and next year in Rome."

Williams' knee injury also forced her to pull out of her last tournament in Miami in March. The French Open will begin on May 26.

American Gibbs pulls out of Open after cancer diagnosis

American Nicole Gibbs said on Monday she will miss the rest of the clay court season including this month's French Open after being diagnosed with a rare form of cancer.

The 26-year-old world No. 116 said that about a month ago a dentist alerted her to a growth on the roof of her mouth and a biopsy revealed she had salivary gland cancer.

"Fortunately, this form of cancer has a great prognosis and my surgeon is confident that surgery alone will be sufficient treatment," she wrote on Twitter, adding that she will have surgery on Friday.

"He even okayed me to play an extra couple (of) tournaments these past few weeks which served as a nice distraction."

The Stanford University product said her goal was to be back for Wimbledon qualifying at the end of June.

"I am feeling extremely grateful for the UCLA health network that's been taking amazing care of me, and for rock solid friends and family who are helping me every step of the way," she said. "See you back on the court soon." — Reuters