His second goal came on a deflection of Matt Estoclet's wrist shot, just when it appeared the Grizzlies and Bulls were headed to overtime.
"It was a 3-on-2," Patterson said. "I was skating up the ice and passed it wide to Estoclet. He cut to the middle and I was just driving to the net.
"Honestly, I didn't see the puck hit my stick. But it hit my stick and and went [top] shelf. It probably would have gone in anyway. But, you know, it's good."
Utah goalie Adam Morrison stopped 24 of 25 shots to help the Grizzlies win in regulation for the first time since Feb. 9.
The win moved Utah four points ahead of the Bulls in the race for seventh place in the ECHL's Western Conference.
The No. 7 seed will avoid league-leading Alaska in the first round and skip the long trip such a series will entail.
"Obviously we've been going through a tough stretch lately," Patterson said. "A lot of guys are battling through injuries, so getting those wins is huge for us right now."
After a scoreless and penalty-free first period, it didn't take long for San Francisco to grab the lead. Dean Ouellet slipped the puck past Morrison only 1:57 into the second period to make it 1-0.
Despite outshooting San Francisco through the first two periods, 27-16, Utah coach Kevin Colley wasn't discouraged.
"We had some really good chances," he said. "Whether we were gripping the stick a little too tight or whatever, I felt confident if we kept it simple and kept working we'd be fine."
R Gaelan Patterson scores goals as Utah defeats San Francisco, 2-1.
• Goalie Adam Morrison stops 24 of the 25 shots by the Bulls.
• The Grizzlies snap a two-game ECHL losing streak.