Mikko Rantanen scored on a slapshot 10 minutes, 23 seconds into overtime after tying the score late in regulation and the Colorado Avalanche rallied for a 3-2 victory over the Calgary Flames on Wednesday night in Denver to take a 3-1 lead in the teams' first-round playoff series.

Moments after Colorado killed off a penalty, Carl Soderberg got the puck and sent a pass to Rantanen, who lined a shot past Mike Smith before being mobbed by teammates.

Philipp Grubauer stopped 35 shots for Colorado, which trailed 2-0 in the third period, with J.T. Compher starting the comeback on a rebound and Rantanen tying it on a power-play goal with 2:50 left.

Elias Lindholm and Derek Ryan had goals for the Flames, the top seed in the West, who face a must-win scenario when the series returns to Calgary for Game 5 on Friday.

Boston 6, Toronto 4: David Pastrnak scored twice in quick succession, Brad Marchand had a goal and two assists and the Bruins held off the host Maple Leafs to tie the first-round Eastern Conference series 2-2.

Charlie McAvoy had a goal and an assist for Boston, Zdeno Chara and Joakim Nordstrom also scored and Tuukka Rask made 38 saves. At 42 years, 30 days, Chara, the Bruins captain, became the second-oldest player in NHL history (behind Chris Chelios at 45) to score a playoff goal.

Dallas 5, Nashville 1: Roope Hintz and Alexander Radulov scored power-play goals on Dallas' first two shots, and the Stars chased goalie Pekka Rinne with an early four-goal onslaught in the first period, beating the visiting Predators to tie the series 2-2.

Hintz added his second career playoff goal in the second period, on John Kingberg's third assist of the game. Ben Bishop stopped 34 shots for the Stars.