Andy Murray came from a set down to beat David Ferrer 5-7 6-2 7-5 in the final of the Vienna Open.
The victory means he moves ahead of the Spaniard in the race to qualify for the World Tour Finals.
Murray, 27, broke his opponent three times in the final set before serving out the match to win only his second title of the year.
The win means the Briton leapfrogs Ferrer, 32, and moves up to eighth in the race to London.
The top eight players at the end of the regular season will qualify.
"It was a good finish to the week," Murray told BBC Radio 5 live after a match lasting two hours 42 minutes.
"Obviously, it was an important match in the race for the Tour Finals in London and it was a very, very tough match but I managed to get through it.
"It was a very long match and both of us were in the locker room struggling, limping around and very stiff and sore so it was a nice one to get through."
|Russell Fuller, BBC tennis correspondent|
|"The prize of 250 ranking points - and the victory over such a close rival - could yet prove crucial in the Race to London, but may not be as valuable as the confidence gained from a long overdue victory. Murray played with real freedom and intent when the match was slipping away, but the Race still has two weeks to run and won't be decided until the final Masters event of the season in Paris."|
The victory was Murray's first against a top-eight player since he won Wimbledon in 2013.
Murray, whose only other title success this year was at last month's Shenzhen Open, will now travel to Valencia for a tournament that carries 500 points before playing in Paris, where there are 1,000 on offer for the winner, in the last event before the season finale at the O2 Arena.
Novak Djokovic, Roger Federer, Rafael Nadal, Stan Wawrinka and US Open champion Marin Cilic have already secured their places in the World Tour Finals, to be held from 9-16 November.
|The six players chasing three places:|
|Race to London position||Player||Nationality|
"I said when I arrived in China that I wanted to try and get to the latter stages of the events I was playing between now and the end of the year and play against the top players to get into the routine and rhythm again," Murray added.
"I was starting to feel good at the US Open a few months ago and I wanted to try and continue that through until the end of the year.
"Obviously, London would be very nice if I can get there but it's also important for seedings at the Australian Open. To be seeded in the top eight there can make a big difference to the draw and hopefully I will be able to do that."
Tomas Berdych also closed in on his place at the World Tour Finals with victory at the Stockholm Open where he also came from a set down to beat Grigor Dimitrov 5-7 6-4 6-4.
The Czech now sits seventh in the world, while Bulgarian Dimitrov's hopes of qualifying for the O2 are fading.
Cilic won the Kremlin Cup with a 6-4 6-4 victory over Spaniard Roberto Bautista-Agut.