With CONCACAF Champions League now underway, some teams will have even more congested schedules than normal. Busy schedules sometimes make it easier to trip a team up, simply because they're tired.

This week's teams on Upset Alert are connected to one semifinal in the U.S. Open Cup through their opponents. Let's take a look at the two teams I think need to be watching their backs this week.

Upset Alert No. 1: Philadelphia Union vs. DC United

For most of the season, DC United has been a pretty bad team. There has been one exception to that "rule," and that has been the US Open Cup.

On Wednesday, they upended the Chicago Fire at Toyota Park 2-0 to advance to the final. It's one of the few times, if any, they've managed to win two consecutive games in all competitions, having beaten Montreal 3-1 at the weekend.

Philadelphia, on the other hand, finds themselves in fourth place in the Eastern Conference, only four points behind first-place New York. They did win the only meeting so far this season between the two clubs, a 3-2 win in Philadelphia on April 21.

I think DC United can pull off the upset because they're hungry to build on their recent successes. They don't really have much to play for the rest of the season, except maybe trying to save coach Ben Olsen's job.

Upset Alert No. 2: Chicago Fire vs. Montreal Impact

I'm sure, going into their Open Cup semifinal with DC United, some Chicago fans might have been thinking about flight plans for the final, considering their opponent only has three league wins this season.

However, I'm sure they weren't planning on having goalkeeper Sean Johnson tell MLSSoccer.com that he was to blame for their 2-0 loss at home.

The Montreal Impact also played on Wednesday, opening CCL play against San Jose, and came away with a 1-0 win over the Earthquakes.

I think Chicago can upset Montreal because they will want to get the bitter taste of the home defeat out of their mouths as soon as possible. Not that it's a long trip, but Montreal will also have to travel for this game after their mid-week victory.

Thoughts? Think I'm loony? Let me know below in the comments.

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