Tyler Colvin set career highs with four hits and five RBIs and Marco Scutaro plated the winning run with a single in the 11th as Colorado held on after blowing a 7-0 lead to beat Washington in a vintage Coors Field slugfest.
Bryce Harper hit a game-tying home run in the top of the ninth for the Nationals, who have scored double-digit runs in three consecutive games for the first time since the franchise relocated to Washington.
The Rockies batted around in the first inning and scored five runs against Nationals starter Edwin Jackson. The biggest blow was a three-run homer from Colvin, who added a two-run single in the second for a 7-0 lead.
Washington took a big chunk out of the deficit with a five-run third inning keyed by Michael Morse's three-run homer, and they made up the rest of the ground with four in the fifth, tying it at 9 on Ian Desmond's two-run homer.
The Rockies regained the lead when Carlos Gonzalez grounded into a double play with the bases loaded in the bottom of the fifth, but Harper turned on a 1-1 slider from Rafael Betancourt for his eighth home run.
Colorado broke the tie in the 11th when Jonathan Herrera doubled with one out, moved to third on Dexter Fowler's deep flyout and scored when Scutaro lined a single to right for his third hit of the day.
Five players in the Rockies' lineup - Fowler, Scutaro, Gonzalez, Chris Nelson and Colvin - had at least three hits as Colorado salvaged a split of the four-game series.
Adam Ottavino (2-0) struck out five and allowed one hit in two scoreless innings for the win. Craig Stammen (3-1) took the loss.
Jackson allowed eight runs on 10 hits in three-plus innings, snapping a string of seven consecutive quality starts.
Colorado starter Josh Outman lasted just three innings and allowed five runs on five hits. Rockies starters have not won in 21 games, matching a club record. The last Colorado starter to earn a win was Christian Friedrich on June 4.
GAME NOTEBOOK: The Nationals scored 33 runs in the final three games of the series. … Rockies OF Michael Cuddyer, who is 2-for-12 on the current homestand, was left out of the starting lineup but entered as part of a double switch. … Outman has not pitched more than five innings in any of his seven starts this season. He has allowed at least four runs in each of his last five outings. … Desmond's home run came against reliever Josh Roenicke, who is his brother-in-law.