Serena Williams looked sharper than in her previous match two months ago as she opened her clay-court season with a routine 6-4, 6-2 win over Swedish qualifier Rebecca Peterson on Monday.
Next up at the Italian Open: Sister Venus Williams in the siblings' first meeting on European clay in nearly 17 years.
Venus, who won her only Rome title 20 years ago, defeated Elise Mertens 7-5, 3-6, 7-6 (4) after more than three hours, requiring nine match points before eliminating her Belgian opponent.
The Williams sisters' last match on red clay came in the 2002 French Open final won by Serena. In their last match in Rome, Venus won their second career meeting way back in the 1998 quarterfinals.
"That's crazy," Serena said. "I vaguely remember that, so I don't really remember. ... We play each other a lot. Seems like every tournament nowadays we meet early. It is what it is."
Serena is now a 37-year-old mother and Venus is 38.
"It doesn't change at all. We're just as fierce, Venus is just as fierce," Serena said. "We both really want to get some match play. We'll both do the best that we can.
Serena leads the career series 18-12.
"I know that she's going to play really well and compete really well," Venus said. "That's a given."
In March at the Miami Open, Serena needed three sets to beat Peterson.
"It's been a while. I haven't played a ton of matches this year," Serena said. "Not my choice, just by force. I really, really actually desperately wanted to be on the tour and to be playing. It felt good to finally be back out. Hopefully, I'll be able to keep it up."
Serena fell behind 3-1 in the first set but then began to take control with her baseline power on a windy day at the Foro Italico.
When Serena ran down a passing attempt from Peterson and replied with a cross-court winner to break for 5-2 in the second set, she let out a scream and bent over as she pumped both of her fists.
In the final game, Serena served two aces and saved two break points before closing out the first-round match.
Serena finished with 28 winners to Peterson's eight, and committed only two more unforced errors than the 58th-ranked Swede, 22-20.
Serena was playing for the first time since withdrawing ahead of her third-round match in Miami because of a left knee injury. The last time Serena played in Rome was in 2016 when she won the last of her four Italian Open trophies.
Serena is playing only her fourth tournament of the season and was unable to finish her last two due to physical ailments.
"I haven't been able to train or practice a lot. I was out much longer than I expected," Serena said. "But I did everything I could to stay fit and to keep my cardio up. I knew that I love the clay season and I wanted to be a part of it."
In men's action, Italy's top player Fabio Fognini wore a shirt featuring a design of Rome's skyline during a 6-3, 6-4 win over Jo-Wilfried Tsonga; and Borna Coric rallied past Felix Auger-Aliassime 6-7 (4), 6-3, 6-4 in a matchup of two of the top young players on tour. Auger-Aliassime struggled with his serve, hitting seven double-faults to Coric's one.
Also, Karen Khachanov overcame a partisan crowd to beat Italian wild card Lorenzo Sonego 6-3, 6-7 (1), 6-3; while last year's French Open semifinalist Marco Cecchinato was inspired by the home fans to beat Alex Di Minaur 4-6, 6-3, 6-1.
Spanish qualifier Albert Ramos-Vinolas eliminated Gael Monfils 6-3, 6-1; and Denis Shapovalov beat Pablo Carreno Busta 6-3, 7-6 (5).
Others advancing on the women's side included Madison Keys, Garbine Muguruza, Johanna Konta and Dominika Cibulkova.
