OK so I'm not a Gambill fan, but can't help it, here goes:
I saw him winning this match and he looked like an angry angry young man. There's no reason for that anger, for god's sake, he just won a match.
He looked like he was going to kill the loser too. IMO all this built-up anger comes from underachieving. Perhaps when he gets some success, like he's hyped up to be, then we may see a happy smile when he wins a match