Sakic reached the 600-goal plateau by scoring into an empty net, becoming the 17th player in NHL history to record the achievement. He joins Brendan Shanahan and Jaromir Jagr, who both achieved the milestone earlier this year with the New York Rangers.
Milan Hejduk had three goals for the Avalanche (28-25-4), which has won two straight. Andrew Brunette added a goal and an assist while Brett Clark had the other.
Jarome Iginla and Matthew Lombardi had two goals each for Calgary (30-20-8) while Craig Conroy finished with a goal and an assist. Former Avalanche Alex Tanguay added three assists.
Iginla opened the scoring at 9:48 of the first period, blasting a pass from Tanguay past Colorado goalie Peter Budaj. Conroy made it 2-0 at 11:57 when his shot to the top corner beat Budaj on the short side.
Sakic cut Calgary's lead to 2-1 with 20.3 seconds left in the period. He converted a Brunette pass, beating Calgary goalie Miikka Kiprusoff on the power play.
Sakic then returned the favour by setting up Brunette for his 20th goal of the season at 5:47 of the second to make it 2-2. But the Flames again took a two-goal lead on goals from Lombardi and Iginla.
Iginla's goal, his 27th of the season, chased Budaj, who was replaced by Jose Theodore after stopping 16 of 20 shots. The move seemed to spark Hejduk, who scored on the power play, then at even strength in the period to tie the score once again.
Clark scored on a slapshot in the third that just got past Kiprusoff before defenceman Rhett Warrener could clear it away. Originally, the play was allowed to continue, but after a video replay, the goal stood.
Lombardi scored his second of the game and 18th of the season to make it 5-5 before Hejduk tipped a Ken Klee point shot past Kiprusoff to put the Avalanche ahead for good.
NOTES: These teams meet again here Saturday night, then Tuesday night in Denver . . . Colorado's Karlis Skrastins appeared in his 490th consecutive game, the longest streak by a defenceman in NHL history . . . Hejduk extended his scoring streak (five goals, four assists) to five games, including three straight multi-point contests . . . Sakic now has a six-game point streak (five goals, eight assists).