Roger Federer, Rafael Nadal, and Naomi Osaka advanced with routine wins in the first of their two matches at the Italian Open on Thursday.
A rainout on Wednesday backed up play, causing the title contenders to try and win their double-headers as efficiently as possible to save energy.
Federer saved all seven break points he faced to beat Joao Sousa 6-4, 6-3, then was to play Borna Coric for a spot in the quarterfinals.
"Good thing was this one was not that physical," Federer said. "Borna is tough. I lost to him a couple of times last year."
Eight-time Rome champion Nadal cruised past Jeremy Chardy 6-0, 6-1 and will meet Nikoloz Basilashvili.
The top-ranked Osaka comfortably beat Dominika Cibulkova 6-3, 6-3 and will next face Mihaela Buzarnescu.
Compared to his attacking display in Madrid last week, Federer's defensive game was particularly sharp.
En route to breaking Sousa midway through the first set, Federer ran down a drop shot with a perfectly timed slide and replied with a delicate, angled put away.
Federer fell behind 0-40 in the next game but then won five straight points to secure a 5-3 lead, closing out the service game with a stretch forehand cross-court passing shot on the full run from the corner — drawing a loud roar from the Foro Italico crowd.
Federer hit 25 winners to Sousa's eight.
Also, Spanish veteran Fernando Verdasco rallied past fifth-seeded Dominic Thiem 4-6, 6-4, 7-5.
Others advancing included Kei Nishikori, Diego Schwartzman, and Jan-Lennard Struff.
Osaka, who can hold on to the No. 1 ranking by reaching the quarters, hit a whopping 44 winners and 12 aces.
"My serve was really good," Osaka said. "I just tried to be really calm."
Kiki Bertens, last week's Madrid Open winner, was tested in beating 17-year-old American qualifier Amanda Anisimova 6-2, 4-6, 7-5.
Also advancing were Garbine Muguruza, Johanna Konta, and Kristina Mladenovic.
Players were distracted by fighter jets above the Foro Italico rehearsing for an air display later. Players often appeared bothered by the noise and flybys.