A rusty Angelique Kerber has suffered a worrying stumble ahead of her Australian Open defence with a quarter-final loss to Elina Svitolina at the Brisbane International.
The German world No.1 only showed glimpses of her best, often when under pressure, as she succumbed to Svitolina 6-4 3-6 6-3 at Pat Rafter Arena on Thursday night.
Kerber was expected to roll on and set up a US Open final rematch with Karolina Pliskova when she dominated the second set but the Ukrainian sixth seed lifted her game superbly in the clutch moments.
In a thrilling final set, world No.14 Svitolina came from a break down to win five of the last six games to progress through to the semi-final against Pliskova on Friday night.
Kerber had hoped to go one better than last year in Brisbane where she lost to Victoria Azarenka in the final.
But Svitolina, who beat Serena Williams at the Rio Olympics as well as Kerber in their last encounter in Beijing, showed from the outset the dual grand slam winner would not have an easy night.
Kerber struggled on serve 24 hours earlier against local wildcard Ash Barty and again battled with her accuracy but stepped up after losing the first set.
She had the momentum going into the final set and it would be a concern ahead of the Australian Open that she couldn't contain the Ukrainian who lifted brilliantly in an imperious finish.
Kerber is entered to play in Sydney next week where she will again be the top seed.