Having seemed invincible since her maiden Grand Slam triumph at Roland Garros, Barty was overhauled in three sets by Riske, who lived up to her name by attacking relentlessly on Court Two.

The result snapped Barty's 15-match winning streak while cutting short her run at a tournament where she had not dropped a set and seemed in complete command.

"It's disappointing right now. Give me an hour or so, we'll be all good. The sun's still going to come up tomorrow," Barty told reporters.

"Overall it's been a hell of a trip ... Obviously it's a tough pill to swallow. In the same breath, it's been an incredible few months.

"New ground for me here at Wimbledon. This is the best we've done.

"Also proud of the fact what we've been able to do over the last eight weeks," she added.

"The consistency we've brought day in and day out, has been next to none. That's one of the best things about this trip."

Barty captured the world number one ranking during her win at the leadup event in Birmingham but the loss to Riske threatened to make her reign a short one.

Third seed Karolina Pliskova blew her chance to snatch top spot with her own defeat to compatriot Karolina Muchova later on Monday, however.

Barty skirted a number of potential controversies in her no-nonsense style, refusing to buy into outrage back home over a number of perceived slights ranging from 'sexist broadcasting' to Serena Williams's ignorance of her top ranking.

The Twitterati were protesting again over the scheduling of her Riske match on Court Two but the former cricketer played a straight bat to reporters' queries, saying: "I'll play on any court I'm scheduled on."

Barty will head to the U.S. hardcourt season with hope, having shrugged off a previously modest record at the Grand Slams with a first fourth-round appearance at the U.S. Open last year.

"We focus on the positives," said the plainspoken Australian.

"The positives of what have been over the last two months, last six months, and for this year, it's been incredible.

"Today wasn't my day, but that's not going to define us as a team, it's not going to define me as a person. That's the most important thing.

"I have some really good memories (of the U.S. Open) from last year. We go back, we knuckle down, train again, then we go again."