Andrew Brownbill, Associated Press
Serena Williams of the US makes a forehand return to Russia's Ekaterina Makarova during their fourth round match at the Australian Open tennis championship, in Melbourne, Australia, Monday, Jan. 23, 2012.

MELBOURNE, Australia — Five-time champion Serena Williams has lost at the Australian Open for the first time since 2008, struggling with her serve and hitting too many unforced errors during a 6-2, 6-3 setback against No. 56-ranked Ekaterina Makarova of Russia.

Williams was surprised by the power of the groundstrokes coming back at her from Makarova, the lowest-ranked player to make the fourth round of the season's first major.

The 13-time Grand Slam winner had seven double faults — including four in one game in the second set — and 37 unforced errors to give Makarova a spot in the quarterfinals.

Williams sprained her left ankle in a warmup tournament at Brisbane two weeks ago, but didn't show any signs of being restricted on Monday.