[PREVIEW] The 2007 MLS champion has yet to hit its stride and is in the midst of a stretch that would be tough for any team, even one that has all its players healthy and available. The Dynamo is missing a few bodies for its semifinal, first leg encounter with Deportivo Saprissa of Costa Rica in the Concacaf Champions Cup Wednesday (10 p.m. ET, Fox Soccer Channel), but it could have two players added from the squad that lost in feeble fashion to New England, 3-0, in its MLS opener last weekend.

Right back Craig Waibel and midfielder Ricardo Clark will be available; both were notable by their absence last Saturday. Brian Mullan struggled at right back in Waibel's place and Richard Mulrooney, while diligent, doesn't have the range and pace Clark brings to the central midfield.

A knee problem will sideline Mullan against Deportivo Saprissa and also injured are midfielders Brad Davis (groin) and Stuart Holden (ankle). Defender Eddie Robinson is bothered by a sore back but is expected to play.

Deportivo Saprissa stunned Mexican club Atlante, 3-0, in the second leg of their quarterfinal series to win, 4-2, on aggregate. Two own goals helped its cause, but the club that was bought by Chivas Guadalajara owner Jorge Vergara several years ago has dominated the Costa Rican First Division this season.

The club features several players who have faced the U.S. national team many times playing for Costa Rica: midfielder Walter Centeno, forward Ronald Gomez, and defender Jervis Drummond and Gabriel Badilla. Armando Alonso finished off a long pass from Gomez for the vital third goal (on aggregate) against Atlante.

Houston coach Dominic Kinnear is still auditioning candidates to partner forward Brian Ching. Chris Wondolowski started against New England and was replaced by young Argentine Franco Caraccio; neither played effectively against the Revs, and a quiet game for Dwayne De Rosario further impaired the Dynamo attack.

In the quarterfinal round against CSD Municipal, De Rosario and midfielder Corey Ashe carried much of the attacking load. DeRosario followed up on a ball kept alive by Ching to score the first; Ashe earned a penalty kick that DeRosario converted to score the second; and another determined run by Ashe set up Wondolowksi for the third.

Houston resumes MLS play Sunday at home against Western Conference rival FC Dallas, then heads to San Jose, Costa Rica for the second leg against Deportivo Saprissa, which is followed by consecutive away games at Kansas City, Los Angeles, and Columbus. For the Dynamo, the end of April can't come soon enough.