Michael Chang knows what it takes to win a Grand Slam title as a player. Lately, as a coach, he has been trying to transmit some of that knowledge to Kei Nishikori while helping guide him to the US Open final.

Chang has been an animated presence in the courtside guest box the past two weeks, including Saturday, when Nishikori beat top-seeded Novak Djokovic 6-4, 1-6, 7-6 (4), 6-3 to become the first Japanese man to reach a Grand Slam title match.

He leans on the railing at key moments. He jumps to his feet and vigorously pumps his fists after some points. He yells encouragement after others.