British pair Jamie Murray and Neal Skupski maintained their bid to claim the last spot at next week's ATP Finals by reaching the Sofia Open final.
Murray and Skupski won 7-6 (7-4) 6-7 (2-7) 10-4 against France's Fabrice Martin and Poland's Hugo Nys.
But it will not be enough to reach the season-ending event in London if Jurgen Melzer and Edouard Roger-Vasselin win their Sofia semi-final on Friday.
Melzer and Roger-Vasselin are assured of qualifying if they reach the final.
That means Murray, 34, and Skupski, 30, face an anxious wait to see if the top seeds can beat Croatia's Marin Cilic and Bosnia and Herzegovina's Tomislav Brkic on Friday morning.
If Melzer and Roger-Vasselin lose, the British pair would then have to beat Cilic and Brkic to secure their spot at the O2 Arena - for the first time as a pair.
As it stands, doubles player Joe Salisbury is the only Briton to have qualified for the event, which is being held in London for the final time before it moves to Italian city Turin from 2022.
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