The Baltimore Stars, above .500 for the first time this season, are in an ideal position to improve their playoff chances when they play host to the Jacksonville Bulls today at Byrd Stadium (WJLA-TV-7, 2:30 p.m.).

At 7-6-1, the Stars trail Jacksonville (8-6). But Baltimore is ahead of Memphis (8-7) for the eighth and final U.S. Football League playoff spot by virtue of New Jersey's 17-7 victory over the Showboats yesterday. There are four games remaining.

Jacksonville defeated Baltimore, 22-14, the first week of the season. In that game, Jacksonville quarterback Brian Sipe, traded before this season from New Jersey to the Bulls after the Generals drafted and signed Doug Flutie, dislocated his shoulder on the first drive with his new team.

Sipe missed 10 games, returned in the second half of a loss to Tampa Bay, then led the Bulls to victories the past two weeks over Houston and Los Angeles. With Sipe and backup quarterback Ed Luther, Jacksonville has won six of its last seven.

More important than Sipe's return has been the rejuvenated play of running back Mike Rozier. The 1983 Heisman Trophy winner from Nebraska played for the USFL's Pittsburgh Maulers last year and did not perform well.

This season, Rozier, acquired as a free agent, has rushed for eight touchdowns and 1,112 yards, second in the league to New Jersey's Herschel Walker.

Kelvin Bryant (869 yards, eight touchdowns) has been the Stars' best runner. He scored once last week when Baltimore defeated San Antonio, 28-10, only the second time this year the Stars have won two straight. In that game, Stars quarterback Chuck Fusina threw three touchdown passes, the most since he threw three against Jacksonville on May 19, 1984.

For the Bulls, strong safety Joe Johnson (shoulder) is out. Nose tackle Pete Kugler (knee), end Don Fielder (knee) and wide receiver Willie Collier (shoulder) will miss the game for the Stars with injuries. Tom Donovan replaced Collier in the victory over San Antonio and scored a touchdown on his first reception of the year.