JOIN USTop seed Li Na’s eagerly-awaited return to action after her stunning Australian Open triumph last month ended in a bewildering loss to a qualifier in the third round of the Qatar Open.
The much-celebrated Chinese player appeared to have turned the match around when she came from behind to lead 3-1 in the final set against Petra Cetkowska, a Czech ranked outside the top 100, only to stumble to a 7-6 (7-2), 2-6, 6-4 defeat.
Defending champion Del Potro beat Paul-Henri Mathieu of France 6-2, 7-6 (2) to reach the ATP World Tennis quarterfinals in Rotterdam on Thursday.
The Argentine had to save two set-points on serve at 5-6 in the second set to move on to next play Latvian Ernests Gulbis, who beat eighth-seed Grigor Dimitrov of Bulgaria 6-4, 7-6.