Losing to the same opponent 18 times in a row would be hard for any player to take, but imagine what it would feel like if you were ranked No.5 in the world, had won five Grand Slam titles and had been the world's highest-earning sportswoman for more than a decade.
It is probably just as well that few people in sport can match Maria Sharapova's mental strength, because her record against Serena Williams would probably have sent anyone else into meltdown long ago.
The American's 6-4 6-1 victory here over the Russian in the quarter-finals of the Australian Open extended an extraordinary sequence that dates back to 2004.
Having won two of her first three matches against Williams, including the 2004 Wimbledon final, Sharapova has since lost 18 times in a row against her. In their last 14 meetings she has won just one set.
After this latest defeat Sharapova said it was "always frustrating" to lose to Williams but insisted that the losses also helped motivate her to try again.
"It's motivating because she's at a different level," Sharapova said. "She makes you go back to the drawing board, not just for me, but for many other players. She makes you work. That's inspiring."
Williams said she had "no idea" whether she went on court against Sharapova with a mental edge but added: "There's something about her game. I like the way she hits the ball. Plus, when I play her, I know automatically I have to step up my game. I think that makes me play better."
Sharapova said she would keep trying to end her losing run.
"I'll have to keep getting to the point where I have an opportunity to play against her, keep finding a way to turn that around," she said. "If I don't have that chance then I don't have the opportunity to try something different."
Sharapova served a career-best 21 aces against Belinda Bencic in the previous round but failed to penetrate Williams, who broke twice in each set.
"I think if you're serving at maybe 180 (km/hr) against somebody other than Serena, that's an ace," Sharapova said.
"Against Serena, as we all know, the return is one of her great strengths.
"She's very explosive. She stays quite close to the baseline. She cuts the ball early. She doesn't give you many angles.
"That's the reason I can't get so many free points against her."
Williams, who appears to be over the knee problem that disrupted her tournament preparations, admitted that she had felt "a little lethargic" at the start of the match.
She also called for medical attention twice, though she appeared reluctant to talk about it afterwards.
"I was just dealing with some food poisoning issues from a few days ago", Williams said. "That was it."
Sharapova has had her own physical issues of late and said she did not expect to compete again until Indian Wells in March in order to nurse the forearm injury that interfered with her plans at the start of the season.
Williams will play Poland's Agnieszka Radwanska, who beat Carla Suarez Navarro 6-1 6-3, in the semi-finals. Williams beat Radwanska in the 2012 Wimbledon decider.
"It will be a good match," Williams said. "She's been playing really well and already this year she's been very consistent.
"She presents a completely different game, an extremely exciting game. So I think it will be a long match and it will be a good match to see where I am."
Jamie Murray and his Brazilian partner Bruno Soares, meanwhile, reached the semi-finals of the men's doubles with a hard-fought 6-7 6-4 7-6 victory over Raven Klaasen and Rajeev Ram, who had knocked out the Bryan brothers in the previous round.
Murray and Soares next play Frenchmen Adrian Mannarino and Lucas Pouille.
Murray is delighted with the success of his partnership with Soares, the duo having already won one title together this year . Murray split up with Australian John Peers in November after three years.
"He's an experienced guy," Murray said. "He's played a lot of big matches and been at the top of the game for the last few years.
"He plays well under pressure. I think that's his biggest strength, that he stays composed, never looks like he's rushing, seems to have a plan of what he wants to do. He trusts himself and hopefully he trusts me as well."