The Uzbek is currently on a six-match losing run on tour with the last win coming against the Serbian teenager Miomir Kecmanovic in the first round of Miami Open. However, he won two matches against Pakistan in the Davis Cup tie last month.
The former world #33 has retired six times since the start of 2017 season, including once at Brisbane earlier this season, which is a major reason for his current struggles on tour.
Denis Istomin entered the main draw of ATP Geneva twice in 2015 and 2016, and won the first round match on both occasions, against Janko Tipsarevic and Florian Mayer, respectively.