Demitra registered his first multi-goal game since Nov. 29, when he recorded a hat trick against Calgary, and the Blues beat the Avalanche at Savvis Center for the first time since Feb. 25, 2000.
But Demitra recorded a power-play goal 4:11 into the second period and Mellanby scored his 13th of the season just over eight minutes later as the Blues registered back-to-back victories for the first time since winning nine straight from Oct. 15-Nov. 5.
Demitra's goal with just under eight minutes to go in the contest moved him past Brendan Shanahan and into seventh on the Blues' all-time goal-scoring list with 157.
Milan Hejduk scored his 15th goal, increasing his points streak to nine games, and Alex Tanguay pulled the Avalanche within 3-2 with just 26.9 seconds left. But Tony Granato suffered his first loss since taking over as Colorado's coach on Dec. 18.