Surprise: Web sports sites are just as competitive as the athletes they cover. Diehards flock to these sites for their fix of scores, news and fantasy leagues, making the field one of the fastest growing on the Internet. MSNBC, ABC, Prodigy and AOL all offer sports content on the Web, but the real heavyweights are ESPN SportsZone, the market leader, and CBS SportsLine, the 3-year-old upstart that wants to knock its block off. SportsZone has about twice the audience of SportsLine and the cachet of ESPN’s 18 years of cable experience. But now SportsLine has a secret weapon: Michael Jordan. It recently signed the Chicago Bulls star to a 10-year, $10 million deal to create his own Web page and answer fan e-mail. The goal: ““I didn’t start this company to be No. 2,’’ says CBS SportsLine CEO Michael Levy.

Both services have heavyweight backers. Last April Disney (which owns ESPN) bought one third of Microsoft billionaire Paul Allen’s Starwave, the Web-design company that runs SportsZone. Meanwhile, SportsLine linked up with CBS last March, after talks with Fox fell through. Neither site is profitable - last year Sports-Line lost nearly $13 million. SportsZone won’t disclose its losses.

SportsLine’s strategy to catch its rival combines self-promotion with expansion, often paid for with equity in the company. Its deal with CBS gave it on-air mentions of the site during the network’s currently feeble sports lineup, and its broadcast of the 1998 Winter Olympics in Nagano, Japan. SportsLine maintains its autonomy, but CBS got its name in the company and a 12 percent stake, with an option to buy up to one third.

Getting Jordan was Sports-Line’s boldest move. ESPN SportsZone has stayed away from athletes, preferring instead to link up with leagues like the NBA and NFL. On SportsLine, Jordan joins Shaquille O’Neal, Cal Ripken and 14 other athletes who have signed with the company to create their own pages. SportsLine is betting that the prospect of e-mailing His Airness will draw enough viewers and advertisers to make his paycheck worthwhile.

Whether SportsLine can win the title belt from ESPN SportsZone is another question. SportsZone execs argue that once bandwidth expands, their relationships with the leagues will give them exclusive access to live video and let them offer the sports nut’s dream: made-to-order game highlights. SportsLine, for its part, plans to use Jordan’s name to take the service overseas and will keep gunning for SportsZone. One more brawl for Net fans to follow.