Houston Rockets All-Star James Harden might be the most difficult player to guard in the NBA, and it's partly because of his ability to draw an incredible number of fouls.

Marcus Smart had the unenviable task of guarding Harden during the Rockets' 123-120 win over the Boston Celtics on Saturday, and after the game he aired his frustrations with the way Harden is officiated, making comments which earned him a $15,000 fine from the NBA.

"When you're playing a guy like that who gets those types of calls, it's pretty much like you're playing in foul trouble," Smart said after the game. "You've got to play really certain. You have to be really solid. You can't really play the defense that you want, because you know nine times out of 10 he's going to get those calls. It doesn't matter whether your hands are up or not. He still gets them.

"We saw that here tonight a few times, and we've seen that every other game. He has a way of using his hands, grabbing us, pulling us into him and drawing those fouls. He's been doing it for a long time. He gets the benefit of the doubt."

Harden has led the NBA in free throw attempts per game for the past three seasons, and this year the NBA implemented a rule, informally dubbed the "Harden Rule," which clarified what is and is not a shooting foul.

It hasn't really seemed to affect Harden, however, as he still leads the NBA with 10.1 free throw attempts per game, right in line with his averages over the past few seasons.