I don't see Fed's forehand to the deuce court/Nadal's BH to be the key. Nadal is not going to be hitting to Fed's FH. He's going to be hitting to Fed's BH, like he always does. The key for Fed is his 1st serve Pct. If he can serve the way he did against Tsitsipas in Dubai, high 70's % for much of the match, he'll have a good chance against Nadal.