"Just got to stick with it," the coach said.
Vegas faces a dire situation. Dallas can win the best-of-7 series in Game 5 at Rogers Place in Edmonton, the hub city for the conference finals and Stanley Cup Final, on Monday (8 p.m. ET; NBCSN, CBC, SN, TVAS).
Since the NHL introduced the conference format in 1981-82, teams with a 3-1 lead in the conference finals have won 34 of 35 series. The lone team to come back and win was the 1999-00 New Jersey Devils, who did it against the Philadelphia Flyers in the Eastern Conference Finals.
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But DeBoer said this is similar to the Western Conference Second Round, when the Golden Knights had a 3-1 series lead against the Vancouver Canucks, ran into a hot goalie in Thatcher Demko and needed seven games to advance.
"We faced some of this in the Vancouver series, and we stuck with it," DeBoer said. "This is a long way from over, and we're going to be a tough out."
In the second round, the Golden Knights lost 2-1 in Game 5 despite outshooting the Canucks 43-17, lost 4-0 in Game 6 despite outshooting them 48-23, and won 3-0 in Game 7 after outshooting them 36-14.
In the conference final, the Golden Knights lost 1-0 in Game 1, which DeBoer attributed to tired legs after playing three games in four nights. They won 3-0 in Game 2, outshooting the Stars 32-24. But then Dallas goalie Anton Khudobin turned into another Demko. Vegas lost 3-2 in overtime in Game 3 despite outshooting Dallas 40-23.
DeBoer emphasized scoring the first goal in Game 4, hoping to force the Stars out of their defensive structure. The Golden Knights got it when defenseman Alec Martinez scored on the power play at 7:44 of the first period, but they held it for less than four minutes.
Dallas forward Joe Pavelski got a lucky bounce when a puck deflected off the stick of Vegas defenseman Nate Schmidt and over the glove of goalie Robin Lehner at 11:34. The shots were 22-6, Vegas, before that goal. Dallas forward Jamie Benn scored on the power play at 19:01, and the Stars protected the lead.
The Golden Knights failed to answer despite a 5-on-3 for 1:10 in the third period, and they lost another game despite a lopsided shot total, this one 33-20, Vegas.
"We've been here before," DeBoer said. "We were in the exact situation against Vancouver with a goalie playing like this and a team playing like this. We stuck with it long enough to get through that. For me, it's perseverance."