After a chaotic Wednesday in Doha, Thursday largely unfolded according to expectations.  Five of the top 10 women advanced to the quarterfinals of this WTA Premier Five tournament, although some of them met greater resistance than others.  Whereas Angelique Kerber and Jelena Jankovic triumphed routinely, Petra Kvitova and Sara Errani needed to battle through third sets.  The easiest passage into the quarterfinals belonged to Agnieszka Radwanska, whose opponent retired after losing the first set.

But one stunning result came today that jolted the entire draw.  Top seed Li Na had not lost a match in 2014, collecting titles at Shenzhen and at the Australian Open, where she did not lose a set from the fourth round onward.  Li did not find her best tennis for much of her second-round victory in Doha, yet she entered her meeting with world No. 133 Petra Cetkovska as a heavy favorite.  Cetkovska had needed to advance through qualifying and was only the 13th-ranked player in that draw.  The Czech had defeated a rusty Sloane Stephens in the first round, but she had struggled to advance past journeywoman Zhang Shuai, so she seemed unlikely to trouble Zhang's compatriot for long.

On the other hand, there was more to Cetkovska's threat than met the eye at first.  She had won her most recent meeting with Li Na, also on a hard court, at the Premier event in New Haven three years ago.  For most of the time since then, injuries had prevented Cetkovska from reaching her potential or a ranking appropriate to it.  Li also has struggled to string together strong results throughout her career, causing many to doubt whether she could duplicate Victoria Azarenka's 2012 and 2013 feats of winning in Melbourne and Doha consecutively.

Those doubts proved well-founded in a 166-minute upset of uneven tennis on both sides.  Each woman reached double digits in double faults (10 for Li, 11 for Cetkosvka) and combined to face 27 break points.  Li in fact produced stronger statistics than Cetkovska in several areas, including more service breaks, and she led 3-1 in the final set.  At that stage, one would have expected the top seed to finish off a qualifier.  But Cetkovska had come from behind in the third set of their New Haven meeting as well, and she showed the same resilience in sweeping five of the last six games. 

Li, who later commented on her discomfort with the damp conditions, can look forward to a silver lining despite her disappointment.  Reaching a career-high ranking of No. 2 next week surely will console the Australian Open champion.  And someone with a long history of injuries who turns 32 later this month cannot expect to produce her best tennis week-in and week-out.  Li must focus on peaking at the right moments of the season.  The Australian Open is certainly one of them, while February is not.

Just one of four Czechs who reached the third round in Doha, Cetkovska must feel elated to have reached the most significant quarterfinal of her career.  The New Haven event in 2011 where she upset Li marked her only previous quarterfinal at a Premier hard-court event, but this Premier Five tournament dwarfs New Haven in status.  Perhaps persevering through the injuries that befell her in 2012-13 has taught Cetkovska how to persevere in other forms of adversity, such as when she trailed Li in the third set today.  A woman who had won five WTA main-draw matches over the previous 18 months now has won three in one week.

Up next for Cetkovska is world No. 9 Kerber, one of five top-10 who have reached the Doha quarterfinals.  (World No. 10 Simona Halep, currently in progress, could become a sixth.)  That match will open play on Friday, with a collision between top-eight foes Kvitova and Jankovic set to follow.