Marvin Harrison missed practice Thursday, making his availability for the Indianapolis Colts' Sunday showdown with the New England Patriots uncertain. The team's eight-time Pro Bowl receiver has missed two of the past three games and gone through only one full practice since bruising his left knee Sept. 30 against Denver. The plan was for him to return to practice Thursday, but he didn't. Before Thursday's practice, coach Tony Dungy said, "If he doesn't practice today, I'd say it's doubtful for him playing. "He's looking forward to it, we're looking forward to it, so we'll see what happens.''