Keon, a key member of the Maple Leafs when they upset the Canadiens in six games in the 1967 Stanley Cup Final, speaks with a voice of experience.
"Everybody knows the Leafs are projected to win the series but they can't look past the Canadiens, or past anybody," said Keon, 81, the four-time Stanley Cup champion with the Maple Leafs who won the Conn Smythe Trophy in 1967 as the most valuable player in the playoffs.
The Maple Leafs, the No. 1 seed in the Scotia North Division, host the No. 4 seed Canadiens in Game 1 on Thursday (7:30 p.m. ET, NHLN, CBC, SN, TVAS). Keon, in 2016 voted the greatest Maple Leafs player of all-time, will be tuned in from his home in Florida.
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"It's important that Toronto win games as quickly as possible because the longer it goes, the Canadiens will say, 'Oh, we can beat these guys,'" Keon said. "And as soon as they start to believe that, Toronto starts to think, 'Oh, maybe we can lose this.' There's doubt and there's optimism, and the Leafs don't want the Canadiens to be optimistic at any time."
It is the first time in 42 years that the oldest teams in the NHL and most storied rivals face each other in the postseason. Not one of the current players on either team was alive when the Canadiens swept the Maple Leafs in the 1979 Stanley Cup Quarterfinals.
Maple Leafs veteran Joe Thornton is the only player on either team who has seen playoff action against the other, a total of 13 games for the Boston Bruins against the Canadiens in 2001-02 and 2003-04.
Players on both sides understand how this series is being viewed in a special light.
"It's a historic rivalry," Maple Leafs forward Joe Thornton said. "And playing against each other 10 times this season (Toronto had a 7-2-1 edge), we definitely know each other. There have been some real competitive games. So now with the next chapter here it's going to get more exciting, more intense. And that's going to be really enjoyable.
"It's going to be great. They've got a great team, we've got a great team. They're getting some guys healthy so it's going to be a competitive series."
Toronto forward Auston Matthews, who scored 14 points (seven goals, seven assists) against Montreal this season, compared this rivalry to one of the best in baseball.
"It's kind of like Red Sox-Yankees, fan bases and organizations with rich histories in this League over the last 100-plus years so it's pretty incredible," Matthews said. "It's been a long time since these two teams met (in playoffs)."
The Canadiens can also appreciate the historical aspect of this series.
Canadiens veteran Eric Staal's love of hockey grew from watching televised Maple Leafs games during his youth.
"Honestly, it means a lot," said Canadiens forward Eric Staal, a 17-season NHL veteran. "I grew up in Thunder Bay, Ontario and watched the Leafs every Saturday night. Throughout my career, every time I got a chance to play against Toronto or Montreal, those are the teams that I grew up watching and fell in love with the game.
"Now, at this point in my career, the opportunity to play them in the playoffs, it doesn't get much better. You've got to embrace it, enjoy it, have fun, play hard and play the way we know we can and hope that, in the end, we get the result we want and move on."
Canadiens forward Brendan Gallagher said he's "really excited" about the seven or fewer games ahead against the Maple Leafs.
"It's the first time since the late '70s that these two historic franchises have played (in the playoffs)," he said. "I've been a part of this rivalry for nine years now and it never gets old. It's going to be awesome for us as players to be a part of. It's going to be special, really emotional… intense, competitive."
It means nothing to Gallagher that Montreal will be cast in the underdog role.
"At no point do we do we really care," he said. "We know what type of group we have, we know what team we're playing against. … We're confident in our group. We know the style that we can play to beat anybody in the League. We've just got to bring it."
Dave Keon with the 1967 Conn Smythe Trophy, awarded to him as most valuable player of the postseason.
Keon remembers well his underdog 1967 Maple Leafs, the last Toronto team to win the Stanley Cup, digging in against the 1965 and 1966-champion Canadiens.
Toronto lost the best-of-7 opener, won two games, lost Game 4, then went up 3-2 after a win in Game 5 in Montreal. On the trip back to Toronto, Keon said that he and his teammates believed they had to end the series in Game 6.
"We said, 'We've got to win it Tuesday night because we don't want to go back to Montreal to play Game 7 on Thursday. Too many bad things could happen,'" he said.
The Maple Leafs defeated the Canadiens 3-1 in Game 6 and won the Stanley Cup.
Keon faced the Canadiens five consecutive seasons in the playoffs from 1963-67, splitting four semifinals and winning the Cup in 1967. In 28 playoff games against the Canadiens, he scored 18 points (nine goals, nine assists), with four game-winning goals. A native of Noranda in northern Quebec, he was steeped in the rich history and boiling rivalry between Toronto and Montreal long before he was hip-deep in the battle of languages and cultures.
Harry Meeking, here with the 1929-30 International League Toronto Millionaires, scored the Toronto Arenas' first-ever playoff goal against the Montreal Canadiens on March 11, 1918. At right, Larry Robinson scored the most recent playoff goal between the Canadiens and Toronto Maple Leafs, the quarterfinal Game 4 clincher in overtime on April 22, 1979.
It's been that way since 1918, the first time the Toronto Arenas -- rebranded the St. Pats in 1920, then the Maple Leafs in 1927 -- and Canadiens, referred to as the "Flying Frenchmen," met in the playoffs. That was a two-game, total-goals semifinal won by Toronto, which defeated the Pacific Coast Hockey Association's Vancouver Millionaires for their first of 13 championships.
The Canadiens hold an 8-7 all-time edge in the postseason, their eight series wins and 42 all-time postseason wins against the Maple Leafs the third-most in franchise history. Likewise, Toronto's seven series wins and 29 game victories against Montreal rank third in its history.
As battle lines are drawn again today, there are two more streaks of note, one of them safe forever:
The Canadiens have won six straight times in the first game of a playoff series against the Maple Leafs, all six on Montreal ice.
"I only played against the Canadiens once in the Stanley Cup Final and we won," Keon said with a laugh. "So, my streak is intact."
NHL.com staff writer Mike Zeisberger contributed to this report
Photos: HHoF Images; Getty Images