The resurgent German, who broke a 27-tournament title drought with victory at the Sydney International in the leadup, is now riding a seven-match winning streak as she looks to recapture the form that propelled her to the 2016 title at Melbourne Park.
Kerber was uncomfortable in her skin as the top seed during last year's tournament, when she lost in the fourth round to American CoCo Vandeweghe, but ranked 21st this year, she looms as a dangerous floater in the draw.
In scorching conditions at Margaret Court Arena, she gave 52nd-ranked Vekic the run-around with a series of deft drop-shots and closed out the one-sided match with a confident cross-court smash.
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Born in the same year of the Australian Open's debut at Melbourne Park, Kerber soaked up a birthday serenade from the terraces during her post-match interview on the court.
"It's just amazing how the time is flying," said Kerber, who struggled for form through a difficult 2017 season.
"I'm feeling good, it's good to win today, of course, on my birthday.
"Now I think the work pays off and it's just the beginning of the year."
(Editing by Amlan Chakraborty)
