MELBOURNE, Australia (AP) Angelique Kerber said before the Australian Open that she wasn't putting too much pressure on herself as the top-seeded player at a Grand Slam tournament for the first time.
Clearly, she is still getting used to being No. 1.
The German player ended Serena Williams' reign atop the rankings after picking up her second Grand Slam trophy last fall at the U.S. Open following her breakout win at last year's Australian Open. Since then, however, her results have been pedestrian - seven tournaments, no titles and a 5-7 record against top-50 players.
Her title defense in Melbourne also ended prematurely in a 6-2, 6-3 loss to American CoCo Vandeweghe in the fourth round on Sunday.
''I was not feeling the ball at all tonight,'' she said. ''I was not playing good from the first point.''
Kerber hasn't looked at all comfortable since the year began. She lost early in her two tune-up events for the Australian Open and struggled to find her rhythm in Melbourne once the tournament began, dropping sets in each of her first two matches.
Against Vandeweghe, the usually aggressive Kerber was simply overpowered, hitting just seven winners to 30 for her opponent. She was up a break in the second set and looked to be regaining control of the match, but Vandeweghe came charging back with pinpoint forehand winners that Kerber just watched go by.
Vandeweghe, a former Wimbledon quarterfinalist, often lacks consistency and can let her emotions and temper get the better of her, but she looked composed in the match and far looser with her groundstrokes than Kerber.
After serving it out, there was no celebration from the American - she merely shrugged her shoulders.
After ending 2016 on a four-match losing streak, Vandeweghe started the season with a new mindset - she wanted to project more confidence on the court and play more freely. She set a goal of making the quarterfinals at the year's first Grand Slam - and she's done just that.
''Going out there and playing an opponent, any opponent, I go out there expecting to win,'' she said. ''It's just another person that's in front of me, whoever it may be, if it's No. 1 in the world, No. 130 in the world, it doesn't matter, it's still an opponent to get in my way of achieving my goals.''
Kerber, meanwhile, will have to find her confidence again. She could lose her No. 1 ranking if Williams wins the tournament, which may help relieve some of the pressure she's felt as the favorite.
''It's just the beginning of the year,'' she said. ''I can still improve my tennis, which is good.''