Istomin started the tournament with the opener against Tunisian Aziz Dougaz with 6-3 3-6 6-3 score in Round of 32.

In Round of 16, Uzbekistan international faced Collin Altamirano from USA, but he easily beat American with 6-3 6-0 score in two straight sets.

Denis will struggle with Indian Ramkumar Ramanathan for a place at the semi-finals at the Challenger Winnetka this evening.