Head to heads are 1-1. Their most recent meeting was in July 2013 at this tournament. Struff won on clay in 3 sets. Mayer won on grass in 2013 in 2 sets.
Mayer lost in the qualifying rounds this week but probably knew he had a lucky loser place in the main draw. Once in the main draw he

beat Ramos in a 3rd set tie break. He served pretty well in that match being broken twice.
Struff played a very strong match in the last round to beat Donskoy in straight sets. He did not face a single break point.
They are quite similar on clay this year. we have a fair chance of 3 sets. Some value on Mayer to take at least a set. He seems to be finding his confidence in the last couple of weeks.
Lay Struff if he breaks serve. He starts around 1.75.