Russia's Svetlana Kuznetsova got a late birthday present under Wimbledon's Centre Court roof on Tuesday with a 7-5 6-4 win over former world No.1 Caroline Wozniacki, who is projected to drop out of the top 50 with the defeat.
The veteran 13th seed's power undid the Dane, who had been seeking her first win at a grand slam this year after being dumped out of the Australian Open in the first round and missing the French Open due to injury.
The 25-year-old, rated the best in the world in 2010 and 2011, could drop as low as 59 when the new rankings are released next month.
Coming into the tournament ranked 45 after injuries to her ankle, knee and wrist, it was the first time Wozniacki, 25, had been unseeded at a major since the 2008 Australian Open and she was visibly gloomy after the match.
"It kind of just sucks right now to be out of the tournament. Yeah, there's not really much else to say," she said.
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"It's been a tough year in general. It's been some injuries, it's been some bad draws.
"But, you know, you just have to keep fighting ...and hope eventually that's going to turn and you're going to take the chances you're going to get."
The crowd was willing the Dane to take the match into a third set as former world No.2 Kuznetsova, who turned 31 on Monday, tightened up and looked like she might fritter away her lead.
But the Russian regrouped to serve out the match with a love game as Wozniacki sailed the ball long off her forehand.
Defending champion Serena Williams stuttered to a low-key and error-strewn 6-2 6-4 victory over Swiss qualifier Amra Sadikovic.
Looking ill-at-ease, as though her quest for an elusive 22nd grand slam title was weighing heavily on her shoulders, Williams struggled with her serve and sprayed balls wide on both sides of the court.
It was Williams's first match since she lost the French Open final to Garbine Muguruza and the American should have had few problems against Macedonian-born Sadikovic, ranked 148th in the world and with little main tour experience.
Williams eventually secured match point when her opponent just missed a lob and sealed victory after challenging a wrong call.
Since earning her sixth Wimbledon championship and 21st Grand Slam title a year ago, Williams has gone 18-3 at majors, with the losses coming in the US Open semi-finals, the Australian Open final and the French Open final.
That led some to surmise that Williams has been beset by nerves as she seeks to equal Steffi Graf's Open-era record.
"I think more or less about winning Australia," Williams said.
"I think about winning the French Open. Didn't happen. I think about winning Wimbledon. I don't necessarily think about winning '22."'
World No.6 Roberta Vinci of Italy also advanced, beating Alison Riske of the US 6-2 5-7 6-3.
