Milos Raonic has overcome a first-set wobble to book his place in the second round of the Australian Open.
The Canadian blasted 30 aces during the four-set contest, which he won 3-6 6-1 6-2 7-6(0) in just under two-and-a-quarter hours.
Hajek took advantage of some sloppy play in the first set, as Raonic made 16 unforced errors.
The Czech - ranked 84th in the world - set up four break points for himself, taking just one as he wrapped up the opener 6-3.
Raonic's response was swift, taking just 25 minutes to destroy Hajek 6-1 and level the scores.
It was a similar story in the third set as Raonic edged towards victory, while Hajek's light was diminishing rapidly.
However, the fourth set was a lot more competitive, owing mainly to Raonic's first-serve misfiring, with only 50% landing in.
Hajek managed to take it to a tie-break, but he was soundly beaten without being able to register a single point.