IT'S CLICHÉ TO say things can't get any worse.

But if the Union comes up short against a hungry Rochester Rhinos team Tuesday night in the U.S. Open Cup, "worse" would be putting it gently.

The Union (2-7-2) is winless in its last five matches and coming off a 1-0 loss to Toronto, which entered at 0-9.

Following the loss, forward Danny Mwanga said it is imperative that the players in the locker room "keep their heads up and try to learn from this game." But with the Union plagued by injuries, a rotating lineup and a nonexistent offense, many have the Union as an underdog against the Rhinos, from the USL Pro League, even with the game at PPL Park (7:30 p.m.).

Open Cup play has been under way for a month, with a new format. Major League Soccer teams receive a bye into the third round against clubs from lower divisions. In a style that mimicks March Madness, teams from five amateur, semi-pro and professional teams battle for the Lamar Hunt Trophy in a tournament that began in 1914 as the National Challenge Cup.

This marks the first time the Union will have homefield advantage and play a non-MLS opponent in the Open Cup. In both of its previous matches, the Union has come up short, falling, 2-1, to Red Bull New York in 2010 and a 4-2 shootout loss to D.C. United last season.

But in the Rhinos, the Union has a formidable adversary. Rochester jumped out to a 6-0 start, but has won once in its last four matches.

The Rhinos also have some history in the tournament. They won the Cup in 1999, becoming the only non-MLS team to win since MLS teams were added to the field in 1996. During that run, the Rhinos beat four consecutive MLS opponents.

If the Union defeats Rochester, then it will advance to a fourth-round game June 5 at home against either the Richmond Kickers or MLS rival D.C. United. Those teams play Tuesday at 7 p.m.

"It's simple, we all know each other," Mwanga said. "We had a good look in each others' eyes and know that it just wasn't good enough [against Toronto]."

Contact Kerith Gabriel at gabrielk@phillynews.com