"Right away when I saw Pav, I knew the puck was coming, just easy job for me to finish there," Hertl said. "... It was a [heck] of a series. The Avalanche did such a great job, and we are for sure happy for a huge win tonight."
Rantanen scored with seven seconds left in the first to make it 2-1.
Colorado appeared to tie the game when Colin Wilson scored from the slot off a pass from Nathan MacKinnon at 7:49 of the second period. But San Jose coach Peter DeBoer challenged for offside, and video review showed Gabriel Landeskog in the zone ahead of the puck before going off for a change.
"I was just as surprised as anybody," Landeskog said of the goal being overturned. "I came off, and all of a sudden two seconds later we score. I didn't think anything of it, to be honest with you. And then we were wondering why they weren't dropping the puck.
"Obviously I was still on the ice. We saw some replays on the bench and from what we saw it could have gone either way. ...
"It's a clumsy mistake, you know. Get off the ice. ... If I could have done something different on that play, I would have jumped the boards a lot quicker."
Donskoi scored with a wraparound at 12:37 in the second to give the Sharks a 3-1 lead. It was his first goal in 40 games dating to Jan. 10.
"It's a time where we thought it was 2-2 and we kind of got caught sleeping, and it ended up being 3-1 shortly after that," Avalanche defenseman Ian Cole said. "So regardless of what happens, how that call turns out, we need to keep playing and we can't let it affect us, and I think we did."
Jost scored to make it 3-2 51 seconds into the third period.