Colvin's shot put the Rockies ahead 5-0 in an inning that saw Colorado send 10 men to the plate and bang out four consecutive run-scoring hits.
Chatwood (4-1) went five innings to earn the victory, allowing two runs on seven hits. The right-hander yielded three walks and struck out one as Colorado evened its three-game set.
Phillies starter Jonathan Pettibone (3-3) was lit up for seven runs (six earned) on 10 hits in just three innings.
John Mayberry launched a two-run homer while Ben Revere went 3-for-5 with an RBI for Philadelphia.