Britain's Johanna Konta is out of the Dubai Duty Free Championships after losing 6-4 6-7 (6-8) 2-6 to Russia's Daria Kasatkina in the last 16.
Konta, the world number 12 and seventh seed, saved seven break points in the first set before taking the opener.
But the British number one blew two match points in the second set tie-break as Kasatkina levelled the scores.
World number 24 Kasatkina then secured three breaks in the third to take victory in two hours and 59 minutes.
Kasatkina broke for the first time on her 10th break point to force the tie-break and had the momentum in the third set against a tired Konta.
In a tight encounter, which finished just before midnight in Dubai, the Briton's total of 63 unforced errors ultimately cost her the chance to progress.
Kasatkina will face fellow Russian Elena Vesnina in the quarter-finals who saw off Latvian fourth seed Jelena Ostapenko.
And Ukrainian top seed Elina Svitolina, the defending champion, will take on Japanese wild card Naomi Osaka in a bid to secure her place in the semi-finals.