Kings 4, Senators 3: Jeff Carter scored his second power-play goal on a deflection of Mike Richards' shot 28 seconds into overtime, and host Los Angeles blew a three-goal lead before beating Ottawa.
Dustin Brown scored twice during the Kings' three-goal first period. Milan Michalek scored the tying goal with 4:27 left in regulation for the Senators.
Ottawa captain Jason Spezza sat out to rest a groin injury.
Blues 3, Blackhawks 2: Alexander Steen's slap shot with 21.1 seconds remaining beat Chicago goalie Corey Crawford and gave host St. Louis its third straight win.
Steen broke down the left side as part of a 3-on-1 rush. He kept the puck and let go a drive from just inside the circle that trickled through Crawford.
The Blues (3-0) matched their best start to a season, also done in the 1969-70 and 1993-94 campaigns.
Flames 3, Canadiens 2: Rookie forward Sean Monahan had a goal and an assist, and Joey MacDonald made 33 saves in host Calgary's win over Montreal.
Sven Baertschi and Curtis Glencross also scored for Calgary (2-0-2). The last time the Flames earned at least one point in their first four games was in 2009 when they had a 4-0 start.
-- ASSOCIATED PRESS