This is the first time they have played.
Dolgopolov has found his form this week after months of erratic displays ( mainly caused by injuries). He has beaten Tipsarevic and Cuevas in straight sets. Tipsarevic was poor but Cuevas was just out played.

Melzer had a tough win over Andreozzi yesterday. Andreozzi looked slightly better in their 1st set but when Melzer nicked it in a tie break it affected Andreozzi a little as the 2nd set progressed.
I think we have value on Melzer to take a set here. Lay Dolgopolov if he breaks in the early games. Three sets looks likely and I favour Dolgopolov to win in the end.