Nathan MacKinnon capped his first career playoff hat trick with an empty-net goal to help the Colorado Avalanche pull away late for a 6-3 win over St. Louis in Game 2 on Wednesday night after the Blues avoided a pregame virus scare that nearly sidelined several players.

The difficult-to-defend MacKinnon now has five goals and two assists in a series the Avalanche lead 2-0.

Joonas Donskoi scored twice and Brandon Saad added an empty-netter.

Trailing 3-0, Sammy Blais scored for St. Louis in the second and Brayden Schenn added another with 9:53 remaining to make it a one-goal game. Schenn's power-play goal followed Nazem Kadri being assessed a five-minute penalty for an illegal check to the head of Justin Faulk.

MacKinnon gave Colorado a 4-2 lead with 4:35 remaining, only to see Mike Hoffman score 15 seconds later. Saad scored an empty-netter with 2:09 left and MacKinnon added another with 11.9 seconds remaining, with fans tossing hats onto the ice in celebration.

MacKinnon's hat trick was the first in the postseason by an Avalanche player in 24 years.

MacKinnon also had an assist.

Philipp Grubauer finished with 32 saves.

Donskoi scored 35 seconds into the game, the second-fastest goal to start a playoff game in Colorado/Quebec history, according to NHL research. The fastest was 29 seconds by Quebec's Wilf Paiement in Game 2 of the 1982 division finals.

The anxiety level for St. Louis increased well before puck even dropped when several Blues players returned positive COVID-19 tests. Later, they were cleared after the results from a lab were investigated with follow-up tests coming back negative.

Among those missing from the morning skate were forwards Vladimir Tarasenko and Jaden Schwartz, along with goaltender Jordan Binnington.

The Blues remained without leading scorer David Perron, who's been on the COVID-19 protocol list since the weekend.

Game 3 will be Friday in St. Louis.