London: At first it had all looked so good for former world number one Caroline Wozniacki at Wimbledon on Friday.
The newlywed Dane raced into a 4-0 lead over China's Zhang Shuai in their third round clash on Court Two.
But that was as good as it got. From there she slipped, via a rambling, rumbling grumble about Hawk-Eye, to a 6-4, 6-2 defeat.
"I thought there was a few ones that I saw way differently," the 28-year-old said, referring to her ongoing irritation with the line-call verification system.
"But it is what it is. You can't really change a Hawk-Eye call. You just have to move on, know what it is. That's really it. I mean, at this point it doesn't matter. It is what it is. Maybe the Hawk-Eye was right. Maybe I just saw it wrong. I don't know.
"Obviously when you think you've won the point and then have to replay, that can be frustrating."
More frustrating, however, must have been letting slip such a commanding lead with barely a whimper. In her last tournament she had let slip a 5-2 final set lead to lose to Aryna Sabalenka at Eastbourne.
But Wozniacki had a swift answer to questions about her form. "I think she played better, and that's really it," she said.
Diagnosed with rheumatoid arthritis at the end of last season, Wozniacki has struggled for consistency this term - reaching the final at Charleston in April, but following that up with first round defeats in three of the subsequent four tournaments.
For Zhang, who becomes the first Chinese woman to reach the Wimbledon fourth round since Peng Shuai five years ago, the victory over the 14th seed marked her first win over a top-20 player all year.
This year's run to the fourth round marks a major upturn in Wimbledon fortunes for the 30-year-old, who had never won a main draw match since her first attempt at qualifying in 2010.
"Can you believe I never win one match before 2019?" she posted on Twitter. "Thanks very much all crowd to visiting and supporting."
Zhang will next face either Viktorija Golubic or Dayana Yastremska for a spot in the quarterfinals.