Keep it in play, spread the games out, angle the backhand, rip the forehand down the line and get a lot of strikes on the Rafa first serve... Rafa has to get as many Thiem serves onto the forehand for a first strike counter barrage, and move Thiem north and south with Rafa being a lot more accomplished in the front court... Rafa's return game a few levels better than Thiem; that will like be a key for Rafa...
Tough match in the offing for both players...
P