The Avalanche showed Pioneer spirit.

Logan O’Connor, inserted in the lineup for the first game in the series by Jared Bednar, scored to tie the Blues in opening period Saturday, and the Avs got back their mojo and their home-ice skating edge back.

Finishing off with two no-brainer, empty-net goals, the Avalanche won Game 3 against the Arch rival Blues 5-2. But it was thisclose for almost 18 minutes of the final period.

The sellout crowd of 18,096 in St. Louis, subdued for much of the evening, was reduced to entertaining itself by singing along with John Denver’s “Country Roads’’ during one late timeout.

But they mostly were singing the blues after starting goalie Jordan Binnington, who had the best stoppage rate in the NHL postseason, had to resign after only 6 minutes, 45 seconds of the game as a result of an upper body (left shoulder) injury he suffered on a three-man collision involving St. Louis’ most dreaded villain, Nazi Kadri.

Not so incidentally, Kadri would tip in a howitzer from Cale Makar to put the Avalanche ahead — to stay — in the second period. And the Avs’ leading scorer in the regular season, who has been inconspicuous during the postseason — assisted on the next goal 3½ minutes later. The constant jeers, and perhaps a public scolding between games by Bednar demanding more involvement by the veteran center, provoked him. In his 12th season (nine in Toronto, the last three in Denver) Kadri was the most inflamed player on both ends of the rink.

The Avalanche had played lackadaisically with a laissez-faire attitude in the second game at The Jar and lost for the first time in five playoff games (including four last year) to the Blues. Yet, Bednar had said he would make some subtle tweaks and expected the Avs to recover quickly, because they rarely flubbed in back-to-back games during the regular season.

The coach came under fire from some, and a few said he should be fired after the Avalanche dropped their first game in six. Bednar was accused of not being fiery. He did fine-tune the Avalanche Saturday, moving captain Gabe Landeskog to the first line and returning O’Connor to active participation for the first time since the Predators’ sweep.

O’Connor responded by scoring.

The 25-year-old right winger took the Avalanche out of their doldrums and away from an indifferent beginning in the opening game in St. Louis, particularly after dependable defenseman Sam Girard was bludgeoned headfirst into the end board behind the goal only 52 seconds into play.

Girard left bloody and battered and was taken to a hospital, where the diagnosis was a broken sternum. He will miss the rest of the playoffs, and the Avs will miss him. Down to only five defensemen for almost the entire game, the Avalanche had to rely more on Devon Toews, who took 38 shifts in 31 minutes. As usual, Cale Makar, one of the three busiest players remaining in the postseason, played 34 shifts and 28:49.

Avs goalie Darcy Kuemper, who has come back from his own dangerous eye-area injury, did what he had to by saving 29 of 31 shots, even though the Blues were on him with a vengeance. But the Blues couldn’t convert either of their power-play advantages and couldn’t score after Ryan O’Reilly made it 3-2 a half-minute before the second intermission.

O’Reilly may have equaled O’Connor with a goal, but he couldn’t match O’Connor’s exuberance when he scored.

O’Connor is another one of those great undrafted free agents who have played for Denver professional sports teams.

The Texan spent three seasons with the University of Denver Pioneers, but nobody in the National Hockey League thought enough of him to pick him in in the draft. So O’Connor, now 25, signed a contract with the local team, the Avs, and he gobsmacked them Saturday.

Makar gloved the puck out of the air at the blue line (barely), immediately dropped it and would make a sensational pass to O’Connor, who switched it on his stick in front of the goal and fooled Binnington to make it 1-1.

The Pioneer got the Avs going and going, and the Blues ultimately were gone.