Serving 'Em Up in Sin City

Jimmy Connors and Martina Navratilova may have made early exits from the U.S. Open at Flushing Meadows, but they're still swinging — this time at each other. On Sept. 25, the two will replay the 1973 battle of — or is it the racquet between — the sexes in which Billie Jean king upstaged Bobby Riggs. Billed as the ''Battle of Champions,'' this pay-per-view event will be broadcast live at 9 p.m. from Caesars Palace in Las Vegas.

''This is not a show like Billie Jean and Bobby. This is Tyson fighting Holyfield. This is war,'' says the macho Connors of the 2-out-of-3-set match ($500,000 goes to the winner and undisclosed appearance fees for each). The more mild-mannered Navratilova sees the challenge as ''much more a battle of egos than a battle of sexes.'' The Nupe-It man will duel it out with some handicaps: he gets only a single serve and will have to cover half the width of each doubles alley.

Though Connors, 40, and Navratilova, 35, have never even hit together, they do have plenty in common. They've won more singles titles than anyone else of their gender (Connors, 109; Navratilova, 159), and they're sticking it out in a sport filled with baby-faced pros who are still taking lessons from Beverly Hills, 90210. ''We've never gone to dinner or anything,'' says Navratilova, ''but I think we feel a kinship because of our age — we're old warriors.''

What will be proven if Connors prevails? ''It proves to me that I can give up half an alley,'' he chuckles. And if Navratilova wins? ''It will surprise some guys,'' she says gleefully, ''Jimmy in particular.''