Konta pays the price for wasting her chances with early Dubai exit
Johanna Konta was unable to take either of two match points as she lost a marathon encounter to Russia's Daria Kasatkina in the second round of the Dubai Championships.
The British No.1 led by a set and 3-1 and looked on the brink of victory at 6-4 in the second-set tie-break, but Kasatkina won four straight points.
The 20-year-old then proved the more consistent in the decider, wrapping up a 4-6 7-6 (8-6) 6-2 win after two hours and 59 minutes to set up a quarter-final against countrywoman Elena Vesnina.
Although Konta led by a set and a break, the match was extremely close, with Kasatkina, ranked 24, failing to take any of seven break points in the opening set. When she did convert to pull level at 3-3 in the second set, it was on her 10th opportunity.
Defending champion Elina Svitolina survived a wobble before beating lucky loser Wang Qiang to reach the quarter-finals.
The top seed needed two hours and two minutes to overcome the Chinese 6-1 5-7 6-2.
Svitolina scraped through after saving nine of 11 break points against the World No.46, who entered the field after the withdrawal of Petra Kvitova.
The Ukrainian got off to a perfect start but saw her game taken apart in the second. However, she bounced back in the third.