Thiem will need to make sure that his plan states that under no circumstances is he going to be standing several feet behind the baseline, otherwise he is going to be in big trouble. Nadal can create angles on this particular court, that he cannot do on any other court in the world, due to the overall dimensions of the space to the sides and in particular to the back of the court. Thiem will need to ensure that he does what Nadal is pretty much the undisputed king of doing, and that is to shrink the court on his side by cutting off the angles.
He will also need to hit deeper towards the center of the court, this will cut of Nadal's ability to generate angles. Fast, heavy hitting shots down the middle, which is where Nadal's forehand is slightly weaker...he's more deadlier off of both sides with his forehand, than he is down the middle. Nadal will cough up more mid court returns, and that is when Thiem needs to understand to step in, and then go heavy into the corners to open up the court, getting Nadal on the run.
Thiem should also take advantage of that massive kick serve that he has, sneak in a few times into the net and volley it away. This strategy should be used occasionally, because it will keep Nadal honest, and prevent him from looping soft returns back expecting Thiem to take the next hit from the baseline, which then allows Nadal to take a massive step forward from the back of the court, and step up onto the baseline. Nadal will need to hit more faster shots as a result, Thiem can use Nadal's own pace of return then to rob Nadal of time, either by hitting heavy down the middle to get the weaker reply, or hard into the corners.
The BHDTL needs to be firing today to offset Nadal camping in the ad side of the court, if Thiem unleashes a few, Nadal will immediately start leaning towards his right in anticipation of that shot. This will leave him exposed on his forehand to heavy deep flat balls, which we know is a strategy that Djokovic and even Federer now uses.
