The Orioles lost their fourth in a row after letting an early two-run lead slip away.
Nolan Arenado began the Colorado comeback with an RBI single in the fifth and Charlie Culberson tied it with the first home run of his major league career in the sixth. Culberson's blast came in his 54th at-bat spread over two seasons with San Francisco and the Rockies.
Rosario snapped a 2-2 tie with a two-run homer in the seventh, Charlie Blackmon tacked on another Colorado home run in the eighth and Todd Helton hit yet another in the ninth.
The rally made a winner out of Juan Nicasio (7-6), who gave up the two runs on four hits in six innings.
Wei-Yin Chen (6-6) surrendered four runs on five hits in 6 1/3 innings to absorb the loss.
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