Boston Celtics guard Marcus Smart can be an irritant for opposing guards -- he's big, strong and physical, with quick hands and an extremely high basketball IQ. He's also fantastic at drawing offensive fouls (put less generously: He's one of the best floppers in the league), and he put that skill to use Thursday. In the closing seconds of Boston's shocking 99-98 victory over the Houston Rockets, Smart coaxed Rockets star James Harden into a pair of offensive fouls that helped seal Houston's fate and capped off a furious second-half comeback from 26 points down. After the game, Smart -- when asked if he prides himself in being "a pain in the ass" -- chuckled. "I guess you could say that," Smart said. "My mom might say that. But nah, I play defense with passion, and defense wins games, and that was proven tonight." That passion, however, can get under an opponent's skin. Harden was visibly frustrated by the end of the game, and that frustration may have had to do with Smart's defense. The powerful guard took away Harden's airspace on every possession in the second half, making it difficult for the superstar to dig into his back of dribbling tricks. Few guards are as strong as Harden, but Smart fits the bill.