Colorado was playing at home for the first time in two weeks and for just the fifth time overall in that span. The gap included a trip to Sweden to play two games against Ottawa last weekend and Matt Duchene, traded by the Avalanche to the Senators on Nov. 5.
Colorado got four players and three draft picks in the three-way deal, and two of those players were on the ice Thursday. Sam Girard, the 19-year-old defenseman, got an assist on MacKinnon's goal at the end of the first period.
Colorado's other new rookie, center Vladislav Kamenev, made his Avalanche debut but left in the second period with a broken arm sustained on a check by Washington defenseman Brooks Orpik.
Landeskog started the scoring 17 seconds into the game and added his second goal when he beat Grubauer on a penalty shot at 4:59 of the third. Landeskog completed his hat trick with a power-play goal at 19:35 of the third. He has eight goals this season to lead Colorado.
MacKinnon made it 2-0 with his sixth goal at 19:53 of the first. Wilson scored at 12:25 of the second and Rantanen added a power-play goal late in the third.
Connolly cut the deficit to 3-1 with his second goal at 18:36 of the second. The Avalanche had a goal disallowed on goaltender interference a minute later.
Avalanche D Tyson Barrie was out with an upper-body injury but should be back in the lineup soon. D Anton Lindholm (broken jaw) and D Patrik Nemeth(lower-body injury) were also out. ... Washington rookie D Christian Djoos was out with an upper-body injury. ... Colorado C Tyson Jost was sent to San Antonio of the AHL for conditioning. Jost has missed eight straight games and 10 of the last 12 with lower-body injuries.