Ivo Karlovic beat Steve Johnson 6-4, 6-4 to reach the final of the Citi Open in Washington D.C., USA on Saturday.

Ivo Karlovic was looking to make his big serve big serve count over fifth-seeded American Steve Johnson at the Citi Open in Washington D.C. And he started by breaking Johnson in the third game the first set.

37 year-old Karlovic was seeking to add to last week's ATP singles title win in Newport, Rhode Island which made him the oldest man since 1979 to win a title - and he took the opening set 6-4 with an ace.

The Croatian, seeded 13th at the hard-court tournament, once again broke his opponent in the third game with a backhand volley cross court.

And the victory was complete as he served another ace to book his place in the final, winning 6-4 6-4

Karlovic will face either second seed Gael Monfils of France or seventh seed Alexander Zverev of Germany in Sunday's final.