Gilles Muller fended off a match point before beating Alexandr Dolgopolov and teenager Alex De Minaur ousted Benoit Paire in the first round of the Sydney International on Tuesday.
Sixth seed Muller has reached the semi-finals of this tournament in each of the last two years, but was in danger of falling at the first hurdle before coming off the ropes to win 6-3 3-6 7-5.
The world number 34 from Luxembourg was on the brink of an exit when Dolgopolov had a match point at 5-4 in the deciding set, but hung in there and progressed to round two after breaking in the next game and serving out the match.
De Minaur had a day to remember in his home city, winning his first ATP World Tour match when the 46-ranked Paire was beaten 6-3 3-6 7-6 (7-1).
Spain-based 17-year-old De Minaur only qualified for an ATP World Tour event for the first time last week and the wildcard entry stunned the experienced Frenchman with a mature showing.
Seventh seed Martin Klizan retired from his match against Andrey Kuznetsov at 3-0 down in the final set due to a foot injury, so the Russian will face De Minaur in the last 16.
Mischa Zverev, Jordan Thompson and Marcel Granollers are all through to the second round.
Marcos Baghdatis is through to round two of the ASB Classic after beating Adrian Mannarino 6-4 6-4 in Auckland.
Dustin Brown will be the next opponent for eighth seed Baghdatis, who progressed as a result of two breaks in the first set and the only one of the second.
Jeremy Chardy and Lu Yen-Hsun saw off Artem Sitak and Karen Khachanov respectively in other first round matches to be played day two.