Joonas Donskoi scored at 15:27 of the third period to make it 4-2. Donskoi played the first four seasons of the NHL career with the Sharks before he signed a four-year contract as an unrestricted free agent with the Avalanche on July 1, 2019.
"I've never had that experience before," Donskoi said of his return. "So there was some extra nervousness maybe. A lot of memories. Good stuff tonight. It was a good experience for me. It was fun to see those guys."
Noah Gregor scored a power-play goal with 44 seconds remaining and Jones pulled for an extra attacker for the 4-3 final.
"We got our chances, but it comes down to inches," Sharks forward Kevin Labanc said. "It's frustrating. We all want to be winning, we all want to be producing."
Landeskog scored at 1:59 of the second period on a rebound to give the Avalanche a 2-1 lead.
"I thought we could have got more," Landeskog said. "I liked the way we played. I liked the way we found each other. We had that attack mentality."