Jack Sock kept his hopes of reaching the last-four of the ATP Finals alive with a battling victory over Marin Cilic, and ended American players’ miserable run without a win at the O2.
The 25-year-old had beaten the Croat in their previous two meetings, coming out on top in the 2016 US Open and in the Davis Cup quarter-finals the same year, and he became the first of his countrymen to record a victory in London.
And in their first best-of-three sets clash – and only contest this year – he extended that record, with a 5-7 6-2 7-6 success in a match that lasted just under two-and-a-half hours.
After losing their opening matches to fellow Boris Becker Group members Roger Federer and Alexander Zverev, both were desperate to keep up the pressure on the group leaders, who meet on Tuesday night.
For Sock, it was a delightful win on his debut after a late dash to qualify by winning the Paris Masters, but for the more experienced Cilic, it’s now seven losses in eight attempts at the O2.
Sock could easily have been disqualified at the end of the first set on another day, after thumping the ball into the crowd in frustration, but he escaped with just a warning.
Sock put pressure on the big Croat early on, and although Cilic survived the first break point with a fine backhand winner, two more errors saw him hand the initiative to the American.
His joy was short-lived, though, Cilic burst into life to break back before holding comfortably to get the opener back on serve.
After trading blows, the pair started to look more resolute on serve but Cilic required a fortunate net cord to survive a break point at 5-5.
Moments later, Sock faced three break points at 0-40 and the world No. 5 converted at the third time of asking as the eighth seed dumped a forehand into the net.
In frustration, Sock thumped the ball into the crowd and was perhaps lucky umpire Mo Lahyani didn’t disqualify him, receiving just a code violation instead.
After his lucky escape, the American broke at the start of the second and this time consolidated the break after a struggle at deuce.
A second break followed for the 25-year-old, with Cilic sending a forehand wildly wide to gift Sock breathing space.
Though the world No. 9 wrapped up the set, it was the Croat who came out of the traps in the third, breaking Sock for a 2-0 lead.
He had been up a break in the final set of his previous match against Zverev before the German recovered and Sock also followed suit to claw his way back into the decider this time around by breaking back at 3-3.
The match went into a tiebreaker and it was Sock who edged his way to victory.