Ana Ivanovic swept ahead with minimal difficulty while drama queen Jelena Jankovic struggled mightily before both Serbian seeds booked into the quarter-finals of the French Open on Sunday, dpa reported.
Second seed Ivanovic advanced in exemplary style, 6-0, 6-0 over outclassed Czech Petra Cetkovska in 54 minutes.
The third-seeded Jankovic, by contrast, faced stiff resistance from Poland's Agnieszka Radwanska before winning 6-3, 7-6 (7-3).
"It was much tougher than it probably looked, or the results indicates," said Ivanovic. "I had to work really hard, I played almost without mistakes today.
"I was really happy with the way I've performed in all matches so far," said Ivanovic. "I'm enjoying going to the court. I want to keep the hard work and keep grinding on the clay."
The winner broke six times against the number 77, while saving the only two break points she faced.
But the Jankovic match was not without a dose of frustration from the third seed, who was treated for a shoulder problem and also nearly found herself in an unwanted third set.
Leading a set and 5-2 after two visits from the trainer, the two-time Rome winner suddenly forgot her game, failing to convert on three match points in the eighth game as Radwanska found fresh hope with a break for 5-3.
Another break of the Serb knotted the contest at 5-5, with Rawdwanska making a match of it as she salvaged five break points in the 11th game to take a 6-5 lead.
Jankovic pulled together enough to level and force a tiebreak, where she played as front-runner to finally get out off court after just over two draining hours on a fifth match point.
"I had pain and pain in the shoulder said the winner, who played with her right forearm heavily taped. "Somehow I managed to win.
"It was tough and I was very disappointed that I let her come back."
The third seed who never seems to be fully fit had a medical timeout after the third game of the second set and a quick massage two games later.
Teenaged Radwanska ranked 15th, owns titles this season in Pattaya and Istanbul.
Both Serbs are chasing Maria Sharapova's freshly gained number one ranking, with various scenarios theoretically possible for a change at the top.
But the Russian would have to fail in her next match for options to start becoming available.
Spanish qualifier Carla Suarez-Navarro continued a charmed run as she put out Flavia Pennetta 6-3, 6-2 in the wake of the Italian's hammering a round earlier of Venus Williams.