The Celtics will be under two forms of pressure when they host the Atlanta Hawks in Game 6 of their Eastern Conference quarterfinal series tonight at the Garden. Hawks forward Josh Smith said exactly that following his team's 87-86 victory Tuesday night in Game 5 at Philips Arena. Smith feels the internal pressure shifts to Celtics, who lead the series 3-2, to win at home and avoid a Game 7 in Atlanta. And Smith said the Hawks plan to exert some external pressure on the C's at both ends of the floor.