Heavyweights Holger Rune and Grigor Dimitrov both survived scares as the tournament's top two seeds safely progressed to the second round at the weather-hit Brisbane International.
Rising Australian Max Purcell threatened to send top-seeded Rune packing before the Danish sensation eked out a 4-6 6-4 6-2 victory on a Monday program decimated by rain.
Second-seeded 2017 champion Dimitrov then also recovered from a set down to deny former world No.1 and five-times Australian Open runner-up Andy Murray 4-6 7-5 6-2 in a battle of two of tennis's old warriors.
"We saw each other a couple of times throughout the week and we're kind of laughing because we've played here 10 years ago or so," Dimitrov, 32, said after outlasting his 36-year-old opponent for the fifth time in 13 career meetings.
Only one other men's match was completed, with Purcell's countryman Jason Kubler among a raft of players to have their first-round matches suspended.
Rune was mightily relieved to have escaped an early exit after Purcell upset the world No.8's rhythm with some daring net play to snatch the first set.
Purcell won 39 of 58 points when he ventured forward, but Rune ultimately proved too steady from the back to start the new year with a win.
"It was difficult, especially at the beginning," Rune said.
"There was a lot of adjustments to make. It's the first match of the season, first day of the season.
"So I just told myself to keep fighting and keep trying to find solutions."
While Dimitrov and 20-year-old Rune moved on, another exciting young gun crashed out, with American Ben Shelton's Australian Open preparations taking an unexpected early hit.
The world No.17, who reached last year's quarter-finals at Melbourne Park and the semis at the US Open, was outplayed 6-3 6-7 (7-5) 6-3 by Russian Roman Safiullin under the closed roof of Pat Rafter Arena.
Left-hander Shelton, the 21-year-old third seed, was unable to break the world No.39's serve and found himself constantly under pressure despite his big weapons.
Safiullin, boasting a Wimbledon quarter-final appearance last July and a win over Carlos Alcaraz in October, chipped away until it eventually told on Shelton.
The favourite grew increasingly frustrated before double-faulting to hand the Russian the decisive break in the third set.
Safiullin then steadied to serve out the match from 0-30 and book a second-round date with Australian world No.40 Alexei Popyrin.
"The main goal was to try to return his serve and get as much as I could in the point and see what I could do," Safiullin said.
"We (Popyrin) played a couple of times ... it's going to be tough, but I'll be prepared for this."
The backlog of matches caused by Brisbane's big wet forced officials to delay releasing the schedule for Tuesday, when 22-times grand slam champion Rafael Nadal was expected to make his eagerly awaited comeback from a hip injury.
Nadal will face former world No.3 Dominic Thiem in his first match in almost a year.
