DENVER -- Alex Wennberg had a goal and an assist, Philipp Grubauer stopped 34 shots, and the Seattle Kraken made a successful playoff debut by beating the defending Stanley Cup champion Colorado Avalanche 3-1 on Tuesday night.

The second-year Kraken became the 13th expansion franchise to earn a win in their first postseason game, according to NHL Stats. Eeli Tolvanen scored the first playoff goal in team history early in the first period, and Morgan Geekie sealed it with a tally in the third.

Mikko Rantanen had the lone goal for the Avalanche, who saw their streak of 10 straight first-round wins come to a halt. It was a string that included two sweeps and dated to 2020.

Alexandar Georgiev made 27 saves. He's coming off a career-best 40-win regular season.

Game 2 is Thursday in Denver.

Grubauer was sharp all night against his former team. He frustrated Colorado's top scorers with one big save after another, while his defense helped neutralize the Avalanche's blazing speed.

The Kraken took a 2-1 lead into the third. They've been virtually automatic when leading after two periods, going 35-1-3 in the regular season. Geekie extended the advantage with a goal off the pads of Georgiev early in the third.

Colorado pulled Georgiev for an extra skater with around 1:35 left but couldn't close the gap.

Grubauer benefitted from a little bit of good fortunate. A shot from Evan Rodrigues in the second period glanced off the top of Grubauer's stick and caromed wide of the net. Later, Bowen Byram's wrist shot hit Grubauer's shoulder and then bounced off the crossbar.

By jumping out to a 1-0 lead, Seattle became the fourth team in the past 20 years to open the scoring in its first playoff game. Tolvanen capitalized on a Colorado turnover to energize the Kraken and stun the crowd.

The lead lasted just over nine minutes as Rantanen tied it up on a pass from Nathan MacKinnon. Rantanen had 55 goals in the regular season, the most by an Avalanche player since the team moved to Denver before the 1995-96 season.

This marked the fifth time an NHL franchise made its postseason debut against the defending champion. It also happened with Columbus in 2009 (against Detroit), Washington in 1983 (New York Islanders), Hartford in 1980 (Montreal) and the New York Americans in 1929 (New York Rangers).