Ylonen made it 3-1 at 8:28 with an unassisted breakaway with a wrist shot over Hill’s glove.
“He’s got really quick hands and a great release,” Canadiens forward Jake Evans said. “So I like the odds when he’s out.”
Just 18 seconds later, at 8:46, Brayden McNabb hit a shot between Primeau’s legs after Theodore’s point shot hit and fell on target, tying Las Vegas at 3-2.
At 11:20, Jonathan Marchessault received a 2-on-1 pass from Ivan Barbashev and fired a one-time shot from the right side to tie the score at 3-3.
Ylonen scored his second goal of the period at 11:53, giving the Canadiens a 4-3 lead.
Theodore scored a power play goal at 16:07 to tie the Golden Knights for the second time at 4-4.
“Their goaltender was great, so if you keep giving him the puck in the end, you’re usually going to get something, and that’s what it turned out to be,” Cassidy said.
Justin Barron scored with 54 seconds left in the final, 6-5.
“We can’t think we’re too good to call every little play,” Evans said.
Note: Canadiens defenseman Arbor Shekai was ejected for the second time after being sent into the corner boards by Barbashev’s shoulder check at 13:11. He suffered an upper body injury and did not return. St. Louis did not give an update after the game. …This was Theodore’s second career four-point game, tying the Golden Knights’ record for most points by a defenseman in a single game, which he first set on Dec. 19, 2017. …The teams combined for six goals in the second period, one shy of the most by either team in a span of this season (Carolina at Colorado on Oct. 21: second-most with seven) ). …Barron scored his 12th goal by a Canadian defenseman this season, tying him with Ottawa and Carolina for the most points in the NHL. …Vegas extended its winning streak against Montreal to nine games (6-0-3) through Dec. 22, 2018, the longest active streak against a single team.