MELBOURNE, Jan 21 (Reuters) - Last year's finalist Alexander Zverev reached the Australian Open third round by defeating Alexandre Muller 6-3 4-6 6-3 6-4 on Wednesday, negotiating a plucky opponent, a rain delay and an injury scare to continue his bid for a first Grand Slam.
After cruising through the opening set and surrendering the next, Zverev gained a foothold in the see-sawing third set when he grabbed a 4-2 lead but a sudden spell of rain halted play on John Cain Arena and threatened to disrupt the German's rhythm.
With the roof closed and the court towelled dry during a near 40-minute break, the third seed got back to work and barely skipped a beat on serve as he comfortably closed out the set to regain control of the contest.
"Credit to him. Two days ago he played 7-6(4) in the fifth against an Australian, Alexei Popyrin, and the way he came out, he played amazing tennis," Zverev said, hailing Muller's battling qualities.
"I thought it was a very high-level match. I didn't know what his energy levels would be like but he's one of the fittest guys on Tour and I'm extremely happy with this match."
Zverev broke Muller for a sixth time early in the next set but the three-times Grand Slam runner-up paused at 2-1 and sat down in his chair with what appeared to be a left leg problem before the 28-year-old soldiered on after medical treatment.
"I took a painkiller and it was fine after that," he said.
"I was a bit scared because it was too close to the Achilles tendon. I just wanted the medic to check it out."
Some big winners followed from Zverev's racket as he looked to shorten his time on court, and he squandered two match points before delivering the knockout blow in the form of a big ace to book a meeting with British 26th seed Cameron Norrie.
(Reporting by Shrivathsa Sridhar in Melbourne; Editing by Ken Ferris)
