Hewitt is such an asshole. At 30-15 3-0, after Lu argued a bit with chair after getting screwed, Lu plays a great rally, barely able to move. Hewitt wins, the stare down, and that horrifying COME ONNNNNNNNNNN he does. What a douchebag.
I think he was a bit peeved that after stalling his service game midway through to have words with the umpire, Lu didn't bother to raise his hand in aknowledgement before receiving the next serve. It's common courtesy after causing a delay to aknowledge the opponent.