In the first set, Istomin easily recorded with the score 6/1, but lose the second with the same scoreline.

In the final set, Denis Istomin stunned Kohlschreiber – 6/3 – to reach seminal of the tournament, where he will face world’s No. 11 Fernardo Verdasko of Spain.

"I think it’s the best match I played of my life," said the 96th-ranked Istomin. "Now I feel like I can play with these guys and beat them."