Andy Murray recovered from losing the first set to defeat Kei Nishikori in a gruelling but entertaining match at the ATP World Tour Finals on Wednesday.
The world number one eventually triumphed 6-7 (9-11) 6-4 6-4 in three hours and 23 minutes at the O2 Arena - the tournament's longest match in history - to gain revenge for a surprise loss to the Japanese in the quarter-finals of the US Open in September.
In overcoming Nishikori in London, Murray moved top of Group John McEnroe and is on course to book a semi-final against the runner-up of Group Ivan Lendl.
There was nothing to separate the two during a marathon first set, Murray failing to capitalise on the only set point in the space of 12 games when, having pushed Nishikori out of position, he somehow found the net with open court beckoning.
That would prove costly during a chaotic tie-break, during which the Briton saved four set points, while wasting two of his own before eventually succumbing when he went long trying to find the line with an angled forehand, giving up his fourth mini break of serve in the process.
Undeterred, Murray promptly broke Nishikori in the opening game of the second set, issuing an ominous roar of determination as he earned a crucial lead.
A powerful cross-court backhand saw Nishikori break in reply and get it back to 4-4, only for the Japanese to hand the initiative straight back, Murray stepping in off the baseline and successfully going after his opponent's second serve with a deep, flat backhand that Nishikori netted.
Murray needed three set points to get the job done in the second, eventually getting back on level terms when Nishikori steered a risky forehand winner off target.
Luck was against a demoralised Nishikori in the third set, as a series of net cords contributed to the 26-year-old giving up successive breaks in the third and fifth games, Murray, despite giving a break back, ultimately running out a relatively comfortable victor after being made to work hard.
Murray  bt Nishikori  6-7 (9-11) 6-4 6-4
Murray - 31/39
Nishikori - 37/49
Murray - 8
Nishikori - 0
BREAK POINTS WON
Murray - 4/7
Nishikori - 2/11
FIRST SERVE PERCENTAGE
Murray - 53
Nishikori - 63
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Murray - 76/48
Nishikori - 72/41
Murray - 130
Nishikori - 121