Alexander Zverev of Germany celebrates match point during the men's semi-final match against John Isner of USA on Day Seven of the Internazionali BNL d'Italia 2017 at Foro Italico on May 20, 2017 in Rome, Italy.
Zverev dominated the opening set only to be pegged back in the second as Isner changed his tactic, coming to the net more as a tie-break was required.
John Isner of USA in action during the men's semi-final match between Alexander Zverev of Germany and John Isner of USA during The Internazionali BNL d'Italia 2017 - Day Seven at Foro Italico on May 20, 2017 in Rome, Italy.
Image credit: Eurosport
The German was 5-0 down in the tiebreak but battled back before Isner took the match to a third set with a forehand winner.
Isner, the first American to reach the semi-finals in Rome since Andy Roddick in 2008, had a chance to break with Zverev leading 3-1 in the final set but the German snuffed out the challenge.
Alexander Zverev of Germany reacts during the semi-final match against John Isner of USA at the ATP Tennis Open tournament at the Foro Italico on May 20, 2017 in Rome.
Image credit: Getty Images
Zverev was ready for Isner and countered accordingly as he secured victory against the 32-year-old and progression to the final.