Carolina dressed more of its top players than Washington, although captain Hurricanes Rod Brind'Amour wasn't in the lineup.
Washington appeared to be in control after Brent Johnson stopped 12 shots through two periods to help the Capitals to a 2-0 lead. But Babin and Cole scored 52 seconds apart against Neuvirth to get the Hurricanes even early in the third period.
Clymer poked a rebound past Carolina goalie Michael Leighton to give the Capitals a 3-2 edge with 2:03 remaining. But Williams sent the game to overtime when he converted a pass from Ryan Bayda with a minute left in regulation.
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Arena: PNC Arena Location: Raleigh, North Carolina
Mike Green Unassisted
Nicklas Backstrom (power play) Assist: Andrew Joudrey, Chris Bourque
Noah Babin Assist: Eric Staal, Cory Stillman
Erik Cole (power play) Assist: Eric Staal
Justin Williams Assist: Ryan Bayda, Trevor Letowski
Ben Clymer Assist: Jame Pollock, Josef Boumedienne
Erik Cole (power play) Assist: Eric Staal, Keith Aucoin