Colorado went 2-for-4 on the power play and 4-for-4 on the penalty kill.
"Special teams were outstanding," Avalanche coach Jared Bednar said. "I would say 5-on-5 I liked our checking. We were skating, we were getting back in the zone, our breakouts were really good, and we didn't spend a lot of time (in the defensive zone)."
San Jose's Tomas Hertl scored on a power play at 10:09 of the third period, but Bednar challenged for offside, and the goal was overturned after video review showed Alexander Barabanov batted the puck into the Colorado zone at 10:03 with Evander Kane in an offside position.
Rantanen scored an empty-net goal with 1:39 left for the 3-0 final.
Bednar didn't have an update on defensemen Ryan Graves and Samuel Girard, who each left the game with an injury. Graves exited in the first period with an upper-body injury, and Girard left in the third with an undisclosed injury after he went awkwardly into the end boards on a hit by Sharks forward Kevin Labanc.
"Obviously, you don't want to see those guys go down," Makar said. "We need them, they're very key players for us. [Girard] plays an incredible amount of minutes, and Graves is a super steady guy."
NOTES: Nathan MacKinnon had his point streak end at 15 games (nine goals, 17 assists), the longest in the NHL this season and the longest by an Avalanche player since Paul Statsny's 20-game streak from Feb. 3-March 17, 2007. … MacKinnon had his streak of having at least one shot on goal end at 263 games. The center had not failed to get a shot since Oct. 13, 2017, against the Anaheim Ducks, when he played 4:29. He played 15:23 on Friday but did not take a shift after fighting Labanc at 9:38 of the third period, serving a fighting major and a roughing minor. … It was the 1,000th win for the Avalanche since relocating from Quebec for the 1995-96 season (1,000-726-101 with 142 ties). … Sharks forward Ivan Chekhovich had one blocked shot in 10:18 in his NHL debut. … San Jose is 0-for-28 on the power play in the past 10 games.