The visitors appeared to be on their way to a gutty win, but Jewsbury popped up with a spectacular volley with 10 minutes to play.
FC Dallas got in front five minutes into the second half when Brek Shea found some space behind the Timbers defense and squared to a completely unmarked Sealy, who had a simple tap-in.
Just a couple minutes later, FCD defender Zach Loyd made his team's job tougher, picking up a second yellow for a tug on Franck Songo'o.
Following a sustained spell of pressure, the Timbers made their advantage pay off in the 79th minute. Jewsbury latched onto a high clearing punch from Kevin Hartman and caught all of a left-footed volley, powering a strike past the Dallas goalkeeper.
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