The wrapping around her sore back and vise grip of pressure squeezed Simona Halep into precarious positions.
Timea Babos turned up the stress levels considerably, too.
Down 1-3 in the decider, Halep was on the edge of an early US Open exit.
The fifth seed bounced her Wilson racquet in frustration then regained her grip.
Scraping running shots back deep in the court, Halep reeled off five of the last six games holding off Babos, 6-1, 2-6, 6-4 to advance to the US Open fourth round.
“I had some problems in the morning and yesterday with my back, but thanks to the physio that gave me the hot back I could play today,” Halep told ESPN’s Rennae Stubbs afterward. “I was not moving easily, but I did everything I could. So I’m happy with the way I fought.”
The 2015 US Open semifinalist permitted just five points on her first serve racing through the 24-minute first set.
The 31st-seeded Babos has a history against the Top 10 and it isn’t pretty. She carried an 0-11 record vs. the Top 10 onto Arthur Ashe Stadium on a breezy overcast day.
An accomplished doubles player who partnered Yaroslava Shvedova to the Wimbledon final in July, Babos began asserting her serve and driving the ball down the lines. She won 10 of 14 first-serve points cruising through the second set.
A surprising aspect of this match was the fact Babos was winning some critical baseline rallies against the normally clean-striking Romanian. Babos drained three errors from Halep breaking to open the final set.
Attacking net, Babos showed her soft hands honed from doubles as she adjusted to a ball skipping off the tape and bumped a self-preservation backhand volley winner to hold for 3-1 at the 93 minute mark. Babos celebrated with a clenched fist and smile.
Down double break point, Babos blasted a 118 mph ace down the middle to save the first break point, but capped a draining 24-shot rally putting a flat forehand into net to drop serve. Both women were bending over gulping in heavy recovery breaths.
Grunting with a bit more authority and amping up her assault on the Babos forehand, Halep powered through a demanding deuce hold—her third consecutive game—for 4-3.
Eager to extend her best Slam singles performance in her 17th major, Babos withstood a stern test in the next game. Raising her clenched fist to her coach, Babos fought off three break points, bolted a backhand right off the sideline and closed a hard-fought hold with a backhand crosscourt.
Spinning in some sub 70 mph serves, Halep essentially dared Babos to beat her with her sometime unruly forehand. The 23-year-old Hungarian wasn’t up to the task. She failed to convert a pair of break points then scattered a couple of forehand errors. Halep held on for 5-4.
Frustrated by being pushed around behind the baseline, Halep bounced her Wilson racquet off the blue court getting some major height off the battered black-and-orange stick and a code violation in the process.
It was a challenging time to make a racket change, but the stress relief soothed Halep, who hammered away at Babos’ increasingly fragile forehand wing. Babos, who had played boldly building the lead, shrunk, dropping the final four points, including dumping her third double fault on match point to end a two hour, eight-minute struggle.
“It was a very tough match,” Halep said. “She played unbelievable starting in second set. Then she had 3-1 in third set. I don’t know how I came back. I felt I wasn’t playing my best, but I fought hard. I did everything I could today. I’m really happy I can finish this match my way.”
Though she was pleased by her resilience, Halep has to be concerned with her back issue and her second serve, which averaged 76 mph but produced several attackable second deliveries as well.
Halep, who raised her three-set record to 11-5, will take on 11th-seeded Carla Suarez Navarro in a battle of brilliant backhands with a quarterfinal spot on the line. Suarez Navarro converted all four break points in a tidy 6-4, 6-3, decision over Olympic doubles gold medalist Elena Vesnina.
Suarez Navarro has split 10 career meetings with Halep, who has won four of their five hard-court meetings. The Spaniard’s lone hard-court win over Halep was a 3-6, 6-2, 6-2 triumph at the 2011 US Open.