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Alexander Zverev kept his hopes of reaching the ATP Finals last four alive with a tricky three-set victory over Diego Schwartzman in London.
After losing his Group Tokyo 1970 opener to Daniil Medvedev at The O2 Arena, Zverev bounced back to record a 6-3 4-6 6-3 win over Schwartzman, whose hopes of reaching the semi-finals are over.
Zverev dropped just three games when beating Schwartzman in the Bett1Hulks Championship final in Cologne last month.
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However, the German knew he was in for a tighter match this time around when Schwartzman broke first in the opening set to lead 2-1.
Undeterred, Zverev responded immediately, and after another break in the sixth game the 23-year-old then saved two break points when eventually sealing the set 6-3.
Break opportunities came and went for both players in the opening two service games of the second set, but Zverev did manage to edge ahead when converting his third break point of the third game.
Schwartzman ended up taking the second set, forcing the match into a decider, but Zverev regained his poise and closed out a victory that ended up being much more difficult than it looked likely to be.
Zverev faces Novak Djokovic in his final round-robin match on Friday, with the latter first in action against Medvedev on Wednesday evening.
Schwartzman meanwhile will look to beat Medvedev in two days’ time to avoid leaving his debut ATP Finals appearance without a win.