Mason made 33 saves, and Ethan Moreau scored in overtime to give the Blue Jackets a 3-2 victory over the Sharks on Saturday and a split of the two-game, season-opening series with the Sharks in Sweden.
"I think it's safe to say that he's probably got his game back to where it was two years ago," Columbus coach Scott Arniel said of Mason. "Last night he got off to a slow start but he was outstanding from that second period on, and tonight all three periods."
Joe Thornton's power-play goal tied it at 2 in the third period, after Swedish-born Kristian Huselius thrilled the crowd when he scored his second of the season on a power play to put the Blue Jackets ahead at the start of the frame.
"It was nice to bounce back and get the win here," Huselius said.
Niittymaki got the start instead of Antti Niemi and made 22 saves. Niemi earned the win in the Sharks' 3-2 victory Friday in the opener.
There were a lot more empty seats at the 13,500-seat Globen Arena compared to Friday.
"I guess it was more fans here the first game but it felt like it was more noise, and they were more into the game tonight," Huselius said. "We had some good times here."
As in the first game, the frantic start was followed by a tight second period that was scoreless.
Arniel earned his first victory as an NHL head coach.
"I didn't want this to drag on," Arniel said. "The longer it goes on you start to worry and wonder when it's going to come but certainly in that dramatic fashion tonight, we had a pretty happy bench and a pretty big group hug behind the bench after Ethan scored."
San Jose hit the post twice in the second period with the score at 2-2.
"I didn't think we were very competitive early in the game," San Jose coach Todd McLellan said. "It's been a long trip."
McLellan added that he has a better idea of what the team needs to do to improve.
"At least we have a measuring tool, we know where we're at, we have some points in the bank that people can't take away from us and we start building on our season," McLellan said.
Upon returning to North America, Columbus will host defending Stanley Cup champion Chicago on Friday. San Jose will face Atlanta on Saturday.