McTavish has scored in consecutive games and now has 19 goals in 64 games this season. The 21-year-old center is third among team leaders in points and goals this season.
With his first of three helpers on the night, Zellweger has found the scoresheet in back-to-back games for the first time in his young NHL career and also owns five points in his last six outings.
McTavish very nearly struck again a few minutes later on a 2-on-1 rush with Ryan Strome, sparked by a defensive zone takeaway and breakout pass by Zegras, but Markstrom lunged his crease across to make a terrific save on McTavish's backdoor one-timer.
McTavish then left the game early in the second period after an awkward collision with Flames defensemen MacKenzie Weegar and Brayden Pachal. No penalty was assessed on the play. McTavish did not return.
The Flames would level the score one shift after McTavish's injury, cashing in on a too many men penalty against Anaheim when Sharangovich fought through a check and tipped home Nazem Kadri's point shot.
Acquired with a third-round pick from New Jersey for veteran winger Tyler Toffoli last summer, Sharangovich has enjoyed a career season in Calgary, now with a personal-best 29 goals and 54 points in 74 games.
Terry had a breakaway look later in the period, sprung by a stretch pass from Killorn, but Markstrom answered with a big glove save to keep the score tied.
Calgary then claimed its first lead just past the midway point of the second as Kuzmenko drifted through the Anaheim slot and outwaited Dostal long enough to bury a snapshot inside the near post.
Kuzmenko scored 39 goals in his rookie season for the Canucks last year, but was dealt to the division rival Flames in the deadline deal for veteran center Elias Lindholm.
Anaheim answered just three minutes later though, with a second chance for Terry this time finding paydirt. When Zellweger's point shot hit Leo Carlsson providing a net front screen, the rebound went right to Terry on the far side of the ice, where the two-time All-Star quickly lifted his shot over the sprawled Markstrom for the power-play goal.