Patrice Bernier scored two in the second half and set up Marco Di Vaio's winner earlier on in Montreal's commanding win.
Marco Di Vaio was caught offside five times, but in the 24th minute his poaching paid off. Patrice Bernier slipped a clever slanted ball through the United backline and Di Vaio curled a shot around Bill Hamid.
In the 50th minute, Emiliano Dudar shouldered Collen Warner off the ball in the box. Bernier stuttered to send Hamid the wrong way, and slipped home his sixth penalty of the season. The 32-year-old has yet to miss one in his MLS career.
Deep in stoppage time, Bernier picked up the ball 10 yards into his own half and slithered through the entire United team before finishing.
The win is Montreal's fifth in a row.
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