ROME, Italy - No.1 seed Simona Halep was able to preserve her perfect record in Internazionali BNL d'Italia quarterfinals after Yulia Putintseva retired due to a lower back injury trailing 6-2, 2-0 after 47 minutes.

Each of the Romanian's four previous visits to the last eight here had seen her navigate this round successfully, having reached the semifinals in 2013 and 2015 and been runner-up to Elina Svitolina in 2017 and 2018. Today, Halep was able to gain the upper hand in a high-quality 47 minutes of play before Putintseva was forced to retire.

This week, Putintseva's on-court time has far exceeded Halep's, with the Kazakh clocking up seven hours and 22 minutes thanks to back-to-back three-set rollercoaster upsets of No.8 seed Petra Martic and No.10 seed Elena Rybakina. After the latter, she had shrugged off any ill effects, saying, "When you get this winning spirit... you actually don't feel that much tired," but today the US Open quarterfinalist's initial attempts to shorten points was evident.

Read more: Putintseva pulls off remarkable Rybakina escape in Rome

This temporarily paid off for Putintseva, who conjured up some of her trademark dropshots and some excellent backhand winners down the line, and brought up the first break opportunities of the match in the third game. But Halep saved both - the first by anticipating the dropshot and flicking a delicate counterdrop - and thereafter took control.

"The big picture is just to be focused against the very fighter players," said Halep about the particular challenges of playing someone like Putintseva. "To break her, I think in my opinion, is just to play a little bit aggressive but also with a little bit of height, changing the rhythm. Because she's changing the rhythm, it is not easy to find your own rhythm. Also the dropshots were not easy, because she has a very, very good hand. But I paid attention. Some of them I got. Then maybe she missed because she felt stressed because I'm there and I'm focused on the ball."

Slamming an inside-in forehand return winner gave her an opening in Putintseva's next service game, and the Wimbledon champion would outlast her opponent to break when the World No.30's slice drifted wide. As the set drew on, it was Halep's down-the-line strikes proving more effective, while Putintseva arguably went to the dropshot well too often - with one going wide to concede her serve for a second time, and with it the opening act.

The two-time Roland Garros quarterfinalist would take an off-court medical timeout between sets, and though she continued to essay some valiant shotmaking on resumption, was unable to keep up with Halep through two deuce games. By now, Halep was also finding success with the dropshot as well as maintaining the upper hand off the ground; after the former World No.1 slammed a backhand winner down the line and Putintseva found the net with a dropshot attempt to drop serve again, the latter called it quits.

Up next for Halep in a bid to reach her third Rome final will be a tantalizing clash of former Grand Slam champions against No.9 seed Garbiñe Muguruza. "Every time I played well against her, [I was] as much as possible aggressive," remarked Halep. If I play my best game and if I feel great physically on court, I have a big chance to win the match. But every time is different, because she's playing so hard. You don't really know what to expect. It's tough every time. So I don't plan for a specific match, because you never know on court."

2020 Rome highlights: Halep through after Putintseva retirement