Fullback Doneil Henry started the play on the go-ahead goal in the 68th minute. Beating a defender in the corner, he sent the ball toward the box and, after rookie Luis Silva swept it toward goal, Wiedeman poked it in.
The 22-year-old was playing in just his 10th career MLS game and was making his second appearance as a substitute since coming over to Toronto last Friday in the deal that sent Julian de Guzman to FC Dallas.
Conor Casey scored in the 23rd minute for Colorado (7-12-1). Jamaican international Ryan Johnson, making up for a flubbed penalty in the third minute, replied for Toronto (5-11-4) in the 51st.
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