Agnieszka Radwanska became Poland's first Grand Slam semi-finalist when she beat Russia's Maria Kirilenko 7-5, 4-6, 7-5 in a Wimbledon quarter-final which took seven and a half hours to complete.
Third-seeded Radwanska's victory over the 17th seed ended four years of frustration after she suffered last-eight losses at Wimbledon in 2008 and 2009 and three defeats at the same stage of the Australian Open.
The 23-year-old - a Wimbledon junior champion in 2005 - will play German eighth seed Angelique Kerber for a place in the final.
Radwanska had swept into the last eight without dropping a set, but she found it much harder to subdue Kirilenko in an error-strewn match disrupted by two lengthy rain delays.
The Pole is unlikely to care about the quality of her victory as she could yet leave London as Wimbledon champion and world number one.
The quarter-final had started at 2:20pm (1320GMT) on Court One but after two delays was suspended at 8:03pm (1903GMT) with the pair locked at 4-4 in the final set and expected to return on Wednesday.
But organisers decided to switch the remainder of the match to the covered Centre Court with Radwanska and Kirilenko resuming their battle at just after 9:30pm (2030GMT).
Thirteen minutes, and four games later, it was all over.
"I'm just very very happy to reach a first semi-final. There are no words to describe it - but the day for me was like 40 hours," said Radwanska.
Back in the afternoon, Radwanska landed the first break for a 3-2 lead and Kirilenko, making her first appearance in the Wimbledon quarter-finals, had to fend off two more break points before rain forced play to be suspended for two hours.
The Pole seemed to lose concentration after the resumpton and squandered two set points on Kirilenko's serve before dropping her own serve as she tried to seal the set.
That served as a wake-up call and Radwanska broke to love before finally converting her fourth set point.
Radwanska was firmly in charge when she broke at the start of the second set, but she dropped serve immediately and did so again after another break midway through the set.
This time Kirilenko made her pay as the Russian snatched the crucial break at 5-4 to level the match.
After another rain break, both players dropped their opening serve of the final set, but the showers returned with the score at 4-4 and 15-0 on Kirilenko's serve.
It was then that it was decided to switch the tie to Centre Court.