hitting a 126 miles per hour ace down the tee on gamepoint to hold serve to reach 5-3.

Then serving for the match with the sun in his eyes, Zverev struck several serves in the 136 miles per hour range including a 135 miles per hour ace down the tee.

However the German also struck two double faults.

Down breakpoint, Zverev hit a 76 miles per hour second serve before netting a forehand to down serve and reach 5-4.

The following three service games remained on serve as the match entered a decisive tiebreaker.

A Zverev double fault combined with two forehand errors and a Fritz crosscourt forehand volley winner sent the American ahead 4-0.

Zverev struck a 137 miles per hour serve down the tee which Fritz netted in a backhand return to reach 4-1.

The American then struck an inside out down the line forehand winner to lead 5-1.

Fritz then reached match point at 6-1 after striking a 132 miles per hour serve down the tee which Zverev netted in a backhand return.

The German then struck a 135 miles per hour serve down the tee which Fritz netted to reach 6-2.

The American netted an additional backhand return to reach 6-3 and his third match point.

The Olympic gold medalist Zverev then struck a crosscourt forehand pass long to end the match after two hours and 21 minutes of play.

Fritz takes on the 29th seeded Nikoloz Basilashvili of Georgia in today's semifinals.