World No 8 and top seed Holger Rune came from a set down to defeat Australian Max Purcell at the Brisbane International on Monday.
The big serving Purcell took the opening set against a rusty looking Rune, but the Dane became increasingly assured as the match wore on and took charge to win 4-6, 6-4, 6-2.
Second seed Grigor Dimitrov was also recovered from losing the first set to defeat former world No 1 Andy Murray 4-6, 7-5, 6-2.
Earlier, Russia's Roman Safiullin ousted third seeded American Ben Shelton 6-3, 6-7 (5/7), 6-3 in a match lasting over two-and-a-half hours.