Iga Swiatek launched her bid for a first Australian Open title with an unconvincing 7-6 (7-5) 6-3 win over Chinese qualifier Yuan Yue under the lights at Rod Laver Arena.
Six-times grand slam champion Swiatek was in all sorts of trouble, broken three times by the hard-hitting Yuan, whose game was levels above her 130th ranking.
But the Pole's backhand proved decisive as she smacked a slew of winners in the clutch points to keep Yuan at bay.
"I was a bit rusty at the beginning, didn't really start well," Swiatek said on court.
"But I knew if I put in the hard work, I will play better so that's what I tried to do.
"I'm happy that it worked, many ups and downs. There are things to work on."
It took some backhand magic for Swiatek to deny Yuan from taking the first set as she served at 5-4.
The Pole won the tiebreak off the same flank, planting her feet on the baseline to unleash a furious inside-out winner before racing to a 3-0 lead in the second set.
With the match slipping away, Yuan called a medical timeout, complaining of tightness in her thigh area, and lay down on the court to let trainers go to work.
When she got to her feet, she promptly broke Swiatek and rallied to 3-2, triggering calls of "Jiayou!" (Come on!) from Chinese fans in the terraces.
Yuan scrapped hard to the finish, saving a match point on serve at 5-3 but there was no denying Swiatek who closed it out with a sizzling backhand return down the line two points later.
Third seed Coco Gauff overcame more early serving issues in a 6-2 6-3 win over Kamilla Rakhimova.
The French Open champion was plagued by double faults last season and hit six more in the first set here.
She shrugged off concerns, though, saying: "It was just the first set. Only had one double in the second.
"I think both of us were struggling on the far side. The sun is right there. I had three doubles in the first game and, once I got through that game, it was pretty much smooth sailing from there."
Australia's Priscilla Hon advanced to the second round after Canadian qualifier Marina Stakusic collapsed on the court in obvious pain when trailing 5-3 in the deciding set.
As tournament officials helped her on to a wheelchair, Hon came to her opponent's aid, holding Stakusic's leg to make sure it stayed extended as they wheeled her out of the arena.
"Obviously I didn't want to win like that," wildcard Hon told reporters.
"I really hope she does feel better. That was quite a scene out there. I had quite a few people come up to me and be, like, 'Wow, that was so dramatic'."
However, Hon did not feel the conditions were that bad.
"I'm Australian, so I should be quite used to it," she said with a smile. "It was definitely warm out there and I think as well with the nerves, the stress levels, it just all impacts it."
Britain's Francesca Jones withdrew in tears while trailing Polish qualifier Linda Klimovicova 6-2 3-2 after struggling with a leg injury that had already forced her out of her Auckland quarter-final.
She had trouble with her movement in the first-round match, where she took a medical timeout after the opening set and needed the physio to attend to her several times in the second before she told Klimovicova she could not continue.
