Usually during the playoffs of any American sport, an injury to a key player effects the team's performance.

The Western Conference playoff matches during the 2012 MLS Cup Playoffs this season have seen the injury bug cause two clubs to be eliminated, both by the Los Angeles Galaxy

The first team to have the injury bug eliminate them from the playoffs were the Vancouver Whitecaps.

Whitecaps center-back Jay DeMerit went down with an injury that took him out of the one-match play-in game with the Galaxy in the 70th minute, and his replacement, Martin Bonjour, had an instant impact on the final score.

Bonjour took down Landon Donovan in the penalty area just one minute after coming on for DeMerit.

Not only did Bonjour earn a yellow card from that foul, Donovan converted the penalty kick he earned as well, and that goal was the difference in the Galaxy's 2-1 win over Vancouver.

The Galaxy once again took advantage of a center-back injury on Wednesday night in the second leg of their Western Conference semifinal against the San Jose Earthquakes.

The hero of the first leg for the Earthquakes, Victor Bernardez, who scored the winning goal at the Home Depot Center in Saturday's 1-0 win in Los Angeles, went down with an injury in the 12th minute.

Some thought that the injury was a blessing in disguise for the Earthquakes since Bernardez had been booked in the fourth minute.

However, a second booking from Bernardez was the least of San Jose's concerns once Ike Opara replaced the center-back.

Opara looked lost in coverage of the Galaxy's forwards for most of the first half.

Opara's most glaring mistake came on the Galaxy's second goal, in which Robbie Keane perfectly timed his run behind the Quakes defense and slotted home the club's second goal after a brilliant pass from Landon Donovan.

The Galaxy went on to win the match 3-1 and advance to to the Western Conference Finals, that will start either Sunday or Monday against the winner of Thursday night's match between Real Salt Lake and the Seattle Sounders.

Whatever club they may face in the next round, the Galaxy may be able to capitalize on injuries to both of those clubs as well.

RSL has a laundry list of center-backs that are injured at the moment, and that could be an issue against the star-studded attack that the Galaxy possess.

Seattle's two injury concerns, Mauro Rosales and Eddie Johnson, should be healthy to play on Thursday, but if either of them pick up an extra knock, it could derail the title hopes of the Sounders.

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