Throughout her 11 seasons in the WTA, Maria Sharapova has played some of her most impressive tennis with her back to the wall. She found herself in that position against world No. 2 Li Na at the Mutua Madrilena Open on Friday, and she responded in familiar fashion with one of her signature comebacks.

Sharapova had won four of her last five meetings with Li, including their last two matches on clay, but the Chinese star also had achieved some notable successes in this rivalry. Li had defeated Sharapova at two majors since the start of 2011, while she held championship point against the Russian in Rome two years ago before narrowly yielding. The Australian Open champion raced out to a 6-2 4-3 lead without dropping her serve, a rare feat against this opponent's dominant return. Two more service holds would have seen her become the only woman to reach the semifinals at all three Premier Mandatory tournaments this year.

That would be the high-water mark of Li's afternoon, though. On the brink of defeat, Sharapova broke serve for the first time to level the second set. Each woman then held serve en route to a tiebreak, which the Russian snatched 7-5 as Li netted a groundstroke. With the momentum in her corner, Sharapova lost little time in exploiting the momentum shift. She broke serve early in the third set and never trailed thereafter, clinching the match when Li double-faulted down match point. (This was the second straight meeting between them to end that way.)

Despite four double faults in the final set, Sharapova saved five of the six break points on her serve. Her clutch play under pressure, long one of her key traits, appears to have returned after she struggled in that area earlier this season. Sharapova had lost three straight three-setters between January and March, but she has won all six that she has contested since then.

Like world No. 2 Li, world No. 1 Serena Williams saw her Madrid campaign end today. The two-time defending champion at the Mutua Madrilena Open withdrew with a thigh strain before an intriguing quarterfinal against Petra Kvitova. Also a former titllist in Madrid, Kvitova is the only women's semifinalist in this year's field who has won the title before. She can expect a stiff test on Saturday from Simona Halep, who routed her in their only previous meeting last August. Rebounding from an early loss in Stuttgart, Halep punctuated her deep run in Madrid wth an emphatic win over the surging Ana Ivanovic in an early quarterfinal. 

The lowest-ranked of the Madrid semifinalists, Sharapova owns the best overall credentials on clay, including the strongest winning percentage on this surface of any woman. The four-time major champion never has lost on clay to any of the other three players remaining in the field. She will square off against the highest-ranked semifinalist, world No. 3 Agnieszka Radwanska, in a rematch of a Stuttgart clash two weeks ago. Sharapova won that match in relatively straightforward fashion, but she will need the same perseverance that she showed against Li to outlast the tenacious Pole.