CHAOS MAY MAKE UCLA VULNERABLE AGAINST USC.

Byline: Jon Wilner Daily News Staff Writer

UCLA's never-ending basketball circus reveals a new act tonight, when the Bruins face USC in their first game since Jelani McCoy's resignation. What's next, a half-man, half-woman?

Not quite, although the chaos continued Tuesday when senior guard Toby Bailey, usually the most unflappable Bruin, was tossed out of practice late in the session. (He is expected to play tonight.)

Frustrated by his last-minute mistakes against Stanford and desperate for a perfect ending to his college career, Bailey has endured an internal struggle in recent days unlike any since his arrival in 1994.

``Usually I have fun playing,'' he said after the Cal game. ``But I'm not having fun now.''

Bailey's dismissal aside, the Bruins' thoughts Tuesday were with McCoy, whose resignation left a hole in the middle of their defense and in their hearts.

``This is the toughest (point) of my career,'' said senior forward Kris Johnson, whose career spans the Princeton loss, Jim Harrick's firing, multiple NCAA investigations and a fall-quarter suspension (with McCoy) for reportedly violating the school's drug policy.

``It's our toughest battle to get over, given we're losing one of the centerpieces of the team. He's a brother. Suddenly, he's gone, and he isn't coming back. It hurts inside.''

Johnson is one of the few Bruins who has spoken to McCoy since his resignation Saturday night. Coach Steve Lavin hasn't, nor has power forward J.R. Henderson - the player whose on-court performance is most affected by McCoy's departure.

``It's hard to take,'' Henderson said. ``He came here and there was an automatic bond. He was fun to be around and fun to play with. It's definitely hard to take.

``We already had things to work on, try to patch things up here and there. Now this. It's like when coach Harrick left last year. Now we have to start all over. It's hard to move on from something like that so quickly.''

The No. 12 Bruins have no choice. Their NCAA Tournament seed hinges on a strong finish, and their seven-game winning streak against USC is at stake tonight.

Of course, the Trojans, losers of four straight, have had their own troubles. Gary Johnson (curfew violation) and Elias Ayuso (missing class) were held out of Saturday's loss to Stanford. (Both are expected to play tonight.) Injuries and disciplinary breaches have forced coach Henry Bibby to use 16 starting lineups, and the margin of defeat to Cal and Stanford (54 points) was the largest in consecutive home games in school history.

Beating their archrival, it seems, is all the eighth-place Trojans have left.

``We really haven't played well,'' Bibby said. ``We're trying to build a program. We have to start someplace, and this is where we've started.''

UCLA won the first meeting 101-84, but the Sports Arena clash is usually close. The Bruins have won five of the last nine there, with the games decided by an average of 4.3 points.

McCoy had 14 points and six rebounds in the Pauley Pavilion meeting last month. Without his presence, and with the chaos swirling and Bailey struggling, the Bruins (19-5, 9-4) are seemingly more vulnerable than at any point this season.

``If we look past SC or don't get focused, we'll be 19-6,'' Johnson said.

And waiting for the sword-swallower.

UCLA at USC

Tipoff: 7:30 p.m. at the Sports Arena.

TV/Radio: Fox Sports West 2; AM-1150.

UCLA (19-5, 9-4) update: Jelani McCoy's minutes will be distributed among reserves Travis Reed, Rico Hines, Billy Knight and, perhaps, Kevin Daley. Reed, a freshman, must regain the form that helped him to back-to-back 14-point games in December, before McCoy's return from suspension. The 6-6 Reed played just five minutes on the Oregon road trip (Feb. 5-7) and none against Cal and Stanford last weekend. The Bruins are 12-0 when shooting 50 percent or better from the field.

USC (7-16, 3-10) update: USC has lost eight of its past nine games, and an upset of the Bruins might be the sole opportunity to redeem the season in any manner. Unfortunately for the Trojans, they enter the game with their own share of turmoil. Point guard Gary Johnson missed Saturday's game for violating team curfew, Elias Ayuso did not suit up for missing classes. USC coach Henry Bibby said both will play tonight, but the Trojans have been without at least one player for the past three games. The Trojans have not defeated UCLA since 1994 and have lost seven straight.

-- Jon Wilner and Scott Wolf

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BOX: UCLA at USC (see text)