Hubert Hurkacz fended off the on-form Koepfer in three sets, only looking in control in the last set.
Koepfer immediately went on the offensive, taking an early break in the first set and winning it 6-4.
The second set was a struggle, with both players trading breaks until Hurkacz took it 7-5.
In the final set, Hurkacz finally took control, winning with two breaks.
The match lasted just over two hours and the final score was 4-6, 7-5, 6-2
Hurkacz keeps his hopes of reaching the tour finals alive as he sits in eighth, Ruud and Norrie are also still in the running.
The Pole makes the fourth round, where he’ll face Duckworth.
Doping sanction victim Simona Halep has gone online to protest her own treatment by anti-doping…
Rafael Nadal lined up for what was to be the final match of his career…
Jannik Sinner took charge in front of his home crowd on Sunday, crushing ATP Finals…
Daniil Medvedev went into meltdown mode on Sunday during a highly charged 6-4, 6-3 loss, with opponent…
Jannik Sinner could well be missing from the opening European clay event of next season…
Rafael Nadal will bring down the curtain on his career next month as he plays his…