LOS ANGELES, DEC. 9 -- Bo Jackson has rocked the sporting world by proving he can excel at two professional sports in the same year. Sunday, when the Los Angeles Raiders' running back travels to Kansas City -- where he plays baseball in the summer -- he might have to display world-class skills in a third sport: dodgeball.

Kansas City Royals fans, both in celebration and derision, showered him with toy footballs out in left field after he announced earlier this year that he planned also to play football. Fans of the Kansas City Chiefs, many of them the same people, have said they will aim a barrage of baseballs at Jackson when he appears in the uniform of the Raiders.

When the 25-year-old announced plans to compete in both sports, he was the center of scorn, ridicule and disbelief. But with his recent performances he has prompted reevaluations.

He made the Seattle Seahawks' pugnacious Brian Bosworth reevaluate his definition of the word "tough" when he rolled over the rookie linebacker for a touchdown and set a team rushing record of 221 yards Nov. 30.

He made the Kansas City Royals, where he plays in the outfield, reevaluate the meaning of the "no football" clause in his contract when he signed with the Raiders last July.

And when he declared that football was just another hobby, stamp collectors everywhere wondered what to call their pastime.

The question remains, amidst this flurry of reappraisement, whether Bo Jackson will continue to pursue his exhausting -- even if lucrative -- two-sport career.

According to him, baseball still is his "first love," and when the time comes to decide which sport to give up "it will probably be football."

When asked after Sunday's game against the Buffalo Bills why he preferred baseball over football, Jackson angrily rejected the question: "Come on man, let that die, everybody knows, okay, just let that die."

Actually, his feelings about the two sports remain something of a mystery and may change from day to day. After catching a touchdown pass and rushing for 78 yards against the Bills, Jackson pronounced: "I'm happy {with my performance}. When it comes to expectations, I do what makes Bo happy. I can't go out there and try to live up to the public's expectations week by week. Sports weren't meant to be that way."

It might make rival cornerbacks and linebackers happy if he opted for baseball, but for most football enthusiasts here -- particularly during this troubled season for Los Angeles -- Jackson leaving the Raiders would be the worst thing to happen since the strike.

In Kansas City -- where Jackson's baseball Royals are heroes and his Raiders are the enemy -- a decision to play only baseball would carry a double blessing. Royals teammate George Brett, who grew up in El Segundo, Calif., where the Raiders have their headquarters, issued a mild dissent. "Watching him play football, it would be a shame not to see him in a football uniform," Brett said.

"I think it's pretty general that everybody {in Kansas City} would want him to concentrate on baseball," Dean Vogelaar, vice president of public affairs for the Royals said. "The fans were disappointed when Bo made the decision to play football . . . {and} they were more disappointed because of the team. The Raiders are the least liked team to play the {Kansas City} Chiefs."

Jackson also offended football players around the league by saying their livelihood was only a hobby to him.

At the time he signed with the Raiders, veteran linebacker Matt Millen said, "If he's not for real, the guys {the Raiders} will abuse him." But these sentiments faded quickly.

"I think all that ended the first time he carried the ball," Raiders tight end Todd Christensen said. "Like they say, it ain't bragging if you can do it, and he can do it."

In his first four starts, he has averaged 7.6 yards a carry. He gains much of his yardage not from fancy footwork but from a style first made popular by the John Deere bulldozer. He is fast and weighs 230 pounds.

Jackson has established himself as a legitimate power hitter. He hit 22 home runs last season, but batted only .235 with 158 strikeouts and sat out most of the second half of the season.

"We would prefer that he play baseball only," Vogelaar said. "If he was playing baseball only he would become a better baseball player more quickly."

Currently, Jackson makes more at his hobby than at his job. The Royals will pay him $383,000 next season, plus $150,000 if he plays out his entire contract. He is expected to play baseball this season, but if he doesn't, he will have to refund half of the $533,000 he already has earned in his first two seasons, a provision he asked for when he signed, Jackson's agent, Richard Woods, said.

His Raiders contract will pay him far more impressive yearly salaries of $668,975, $748,499, $840,184, $960,886 and $1,101,456 through the 1991 season. The Raiders paid him a $500,000 reporting bonus, and will pay him another $500,000 if he returns next year. And, if he stays all five years of his Raiders contract, he will collect a $2.1 million annuity, beyond his salary.

Still, he says baseball in Kansas City is his No. 1 priority.

But this Sunday he will be in Kansas City to play football for the Raiders against the Chiefs. Arrowhead Stadium is almost sold out, meaning the crowd will be nearly twice as large as usually turns out to watch the 2-10 Chiefs.

"Half of the people, maybe 60 percent will be booing him; 40 percent are going to be cheering like crazy for him," Ed Bieler, a talk-show host on Kansas City radio station KCMO told the Los Angeles Times.

"I'm just going to go there and have fun," Jackson said, "and dodge baseballs."