Serena Williams will take on sister Venus in the second round of the Italian Open more than two decades after they last met on the red clay of Rome after both advanced in different styles.
Four-time Rome winner Serena, 37, returned after two months out injured easing through 6-4, 6-2 against Swedish qualifier Rebecca Petersen.
But 38-year-old Venus, whose only Rome title came back in 1999, needed over three hours to battle past Belgian Elise Mertens 7-5, 3-6, 7-6 (7/4).
Serena has not played since a hard-fought three-set win also over Petersen in the second round at the Miami Open in March before withdrawing with a knee injury.
The 23-time Grand Slam winner -- now ranked 11th -- also withdrew from Indian Wells in March complaining of illness.
Watched by her husband Alexis Ohanian, Serena sealed victory on her second match point against her 64th-ranked opponent after 76 minutes on court.
Despite her lack of practice, tenth-seeded Serena was never threatened by Peterson, despite 22 unforced errors by the American in the first set.
It will be another family affair on the courts of the Foro Italico, when she plays Venus, with the sisters last meeting in 1998, 21 years ago.
"That's crazy," laughed Serena.
"I mean, it was like the semifinal or the final. No, the quarterfinal? I vaguely remember that.
"We play each other a lot. It seems like every tournament nowadays we meet early. Yeah, it is what it is. We'll see."
Venus, meanwhile, came out on top of a tight contest that went all the way to a third-set tie-break despite letting the Belgian back in by missing six match points on her serve.
She missed a further two match points as Mertens battled to level the set at 6-6, before finally taking the match in the tie-break and setting up a 31st clash with her sibling.
In the men's section, Italian Fabio Fognini said he was hoping to do "something big" at home as he beat France's Jo-Wilfried Tsonga 6-3, 6-4 to advance to the second round.
"I'm happy, of course, happy because especially for me here, it's always tough to play," said the 31-year-old, who came through on the red clay of the Foro Italico in 83 minutes.
Tsonga, now ranked 92nd, missed much of 2018 after knee surgery.
The Frenchman had won four of the pair's five meetings but was broken in each set, with Fognini saving five of the six break points.
Fognini will next play either Moldovan Radu Albot, who beat him at Indian Wells, or French qualifier Benoit Paire.
French 15th seed Gael Monfils crashed out in straight sets to Spaniard Alberto Ramos 6-3, 6-1.
Canadian Denis Shapovalov beat Spaniard Pablo Carreño-Busta 6-3, 7-6 (7/5) to advance to the second round.
Shapovalov, 20, will next play world number one and Madrid Open champion Novak Djokovic.