The 7-year-old Dream Away mare left alertly and tucked in third early behind pacesetter Nice N Nice. Nice N Nice then scooted to fractions of 27 and 55.3 while Monochromatic mounted her attack first over to three-quarters in 1:24.2.
The two dueled through the stretch with Monochromatic surging by late for a narrow win.
Nice N Nice held second while No Bad Luck charged home for third.
Trained by Dylan Davis, Monochromatic has now won nearly half her 15 starts in 2012 with seven wins and nearly $90,000 in seasonal earnings, with a lifetime bankroll at $480,960.