Today's nationally televised game between the Houston Gamblers and the Baltimore Stars in Houston (WJZ-TV-13 at 2:30 p.m.) could signal a changing of the guard in the U.S. Football League.

Last year, Houston -- despite becoming the first expansion franchise in professional sports history to win a divisional crown in its inaugural season -- lost in the first round of the playoffs to Arizona; the Stars, then in Philadelphia, won the championship.

Five weeks into the 1985 season, the Gamblers are the only undefeated team in the league and Baltimore has a 1-3-1 record.

It hardly takes a genius to figure out why Houston has been so successful. The Gamblers don't have the league's most highly publicized quarterback -- Doug Flutie belongs to New Jersey -- but they do have the most productive, Jim Kelly. Kelly leads the USFL in passing with 1,926 yards and 19 touchdown passes, over 800 yards and seven touchdowns ahead of his nearest competitor, Bobby Hebert of Oakland.

"Obviously Kelly is very skilled, and you have to change your defensive scheme a little bit when you face him," said Baltimore's defensive backs coach Dominic Capers. "They usually go with four wide receivers and throw 90 percent of the time."

Normally, Baltimore could counter with star running back Kelvin Bryant. But Bryant, who injured his right hamstring in practice two weeks ago and aggravated it in last week's loss to Birmingham, is doubtful for today's game. Bryant, who did not practice during the week, is not expected to suit up.

Houston does not use the pass as a surprise. Mostly, it uses a one-back offense, and at times the Gamblers have no runners in the backfield, sending out five receivers. Thus, the Stars' nickel back safety, Scott Woerner, will be utilized often.

"Their skill people fit their offense, small quick guys that can really move. It's the kind of situation that no matter what the score is, you can't relax. He (Kelly) is that good."