Struff 2.46, Monfils 1.67
Monfils won their only previous meeting. That was on clay in the French Open 2014. He won in straight sets.
Monfils has the stronger game on hard courts but struggled a little in the last round. He had some injury issues last season after really pushing himself in 2016 and may not be 100%. He needed 3 sets to beat Lorenzi who is much more comfortable on clay.
Struff had 3 decent weeks on hard courts last season. He beat Tomas Berdych in 3 sets in the last round. His first serve was excellent when it found the target but the second serve looked vulnerable.
Not easy to predict this one but I am going with Monfils. His last match will hopefully have blown the cobwebs away and he will be more settled today. Wait for 1.80 before backing him. This match really rests on how close to full fitness the Frenchman is.