Racquet-smashing Alexander Zverev is breathing easy again after surviving a huge fright to join fellow title hopeful Dominic Thiem in the Australian Open second round at Melbourne Park.
Backing up after a draining ATP Cup campaign, Zverev had to battle back from a set down to deny American Marcos Giron the biggest scalp of his career on Monday.
The sixth seed punished his racquet to let off some steam as he battled to avoid dropping the first two sets in a tense 6-7 (8-10) 7-6 (7-5) 6-3 6-2 victory on Margaret Court Arena.
"He played incredible. He knew that on a big stage, against a top-10 player, he needs to come out firing, be at his best and he had me on the ropes there," Zverev said.
"That second-set tiebreaker could have gone either way and I don't want to go down two sets to love."
Zverev's escape followed Thiem's far more routine 7-6 (7-2) 6-2 6-3 win over Mikhail Kukushkin.
The pair last year featured in the first grand slam final since 2014 not featuring any of tennis's big three - Roger Federer, Rafael Nadal and Novak Djokovic - and again loom as two of the biggest threats to end that trio's 15-year domination of the Open.
Thiem, who took bragging rights from Zverev in that US Open title decider after recovering from two sets down against the German, will play Dominik Koepfer in the second round.
Former champion Stan Wawrinka and the power-serving Milos Raonic remain on track for an explosive early-round showdown after also making impressive starts to their campaigns.
Wawrinka, the 2014 Open winner, underlined his title credentials with a comprehensive 6-3 6-2 6-4 win over Portugal's Pedro Sousa.
Switzerland's three-time major champion fired down seven aces and did not face a single break point in storming into the second round in one hour and 36 minutes.
Wawrinka will face Hungarian Marton Fucsovics next before potentially meeting 14th seed Raonic in round three.
Raonic was equally untroubled in his opener, crunching 17 aces in his 6-3 6-3 6-2 win over Argentine Federico Coria.
The former Wimbledon runner-up will play Corentin Moutet on Wednesday for a place in the last 32 after the Frenchman wore down Australian John Millman in five sets, 6-4 6-7 (4-7) 3-6 6-2 6-3.
Moutet's countryman Gael Monfils was the first major seeded casualty, the world No.11 falling in five sets to Finnish youngster Emil Ruusuvuori.
Remaining the best player of his generation yet to win a grand slam, the 10th-seeded Monfils went down 3-6 6-4 7-5 3-6 6-3 in a three-hour, 46-minute boilover.
World No.12 Denis Shapovalov came from a set down to beat rising star Jannik Sinner 3-6 6-3 6-2 4-6 6-4 in a five-set thriller.
Sinner, a quarterfinalist at last year's French Open, converted just three of his 20 break point opportunities.
Shapovalov will now take on Australian Bernard Tomic in the second round.
Former world No.4 Kei Nishikori bowed out after suffering a 7-5 7-6 (7-4) 6-2 loss to world No.16 Pablo Carreno Busta.
Grigor Dimitrov beat former world No.3 Marin Cilic 6-4 6-2 7-6 (7-5).
Other day-one winners included Reilly Opelka, the American who last week claimed "no one feels welcome" in Melbourne because of the quarantine conditions brought on by the global pandemic.
Now assured of a $150,000 minimum pay day, Opelka advanced to the second round with a 6-3 7-6 (7-2) 6-3 win over Taiwan's Yen-hsun Lu.