Ovechkin extended the lead to 4-1 at 10:25 of the third period, scoring on a one-timer from the left circle off a pass from Conor Sheary on a power play.
John Carlson made it 5-1 when he shot into an empty net from his own goal line at 15:40. Garnet Hathaway then scored at 19:18 for the 6-1 final.
"To me, frustration's taken over for some reason," Brunette said. "When you get frustrated, it usually means you're not working hard enough. Our compete has not been what it has been all year. It could be nerves, but we have to find a way."
NOTES: Florida was held to one goal or fewer in regulation for the first time since Jan. 21 (2-1 shootout win against the Vancouver Canucks). … Huberdeau has 18 playoff points, tying Ray Sheppard for the most in Panthers history. … Ovechkin scored his 72nd playoff goal to tie Esa Tikkanen and Patrick Marleau for 14th in NHL history. … Oshie scored his 14th postseason power-play goal with Washington, passing Peter Bondra for the second-most in Capitals history behind Ovechkin (27). … Panthers defenseman MacKenzie Weegar had a game-high nine hits.