DENVER – It's probably not going to be the most electric atmosphere when the Dodgers get to Coors Field for a three-game series with the last-place Colorado Rockies starting tonight, which is exactly what manager Don Mattingly fears with his team fighting hard to hold onto the NL West lead."Leaving here is the tough one," Mattingly said while seated in the AT&T Park dugout, where his team just played its second-to-last series with the second-place San Francisco Giants.