Carey Price, rested Wednesday, made 29 saves. He is 4-0-0 in four starts for the Canadiens (7-0-1) since missing the first three games with the flu.
"The number of big saves he comes up with is pretty impressive, but again, not surprised," Mitchell said. "He makes it look easy, it's ridiculous. It's so nice to have him on our team."
Alex Killorn scored for a third straight game to give Tampa Bay (5-2-0) a 1-0 lead at 16:08 of the second period.
It was Killorn's second three-game goals streak of the season. He leads the Lightning with six goals in seven games after scoring 14 goals in 81 games last season.
Ben Bishop made 23 saves for Tampa Bay, which lost for the first time in six games against Eastern Conference teams.
"You've got to get more shots if you want to win against Carey Price," Killorn said. "He's just too good of a goalie to not get clear shots in."
The Lightning won the first two games of their six-game road trip.
"It's weird, because I don't know if that was the most exciting game ever played, but you have two really good teams that can skate and check, and two teams are checking each other," Tampa Bay coach Jon Cooper said. "Like, who got the first one, Galchenyuk? That's a sick play he's got to make. That's on and off the stick. Not a lot of guys can do that. That's what it took to beat (Bishop). Our goal, it's a great pass. World class goalies don't have chances on those. The third one, what was that, Pacioretty? Comes whipping around the corner. He's scored a few goals in his career.
"Look at the goals that went in, they weren't gifts. They got the extra bounce and we didn't."