Despite speculation to the contrary, Wednesday night's game between the Royals and White Sox went on as planned.

The White Sox announced several steps to beef up security for the game.

They include more people to watch each foul line and checking ticket stubs more frequently. There also will be more public address announcements reminding fans of the penalties for going on the field.

Tuesday night at U.S. Cellular Field, first base umpire Laz Diaz was attacked by a fan who came out of the stands.

PAST CHICAGO INCIDENTS

Tuesday night, U.S. Cellular Field: After three fans had earlier disrupted the game by running onto the field, a fourth ran on the field in the eighth inning and tried to tackle first-base umpire Laz Diaz, wrapping his arms around Diaz's legs. The fan, who has not yet been identified, will likely face charges. The three men, all in their 20s, who ran onto the field earlier in the game were charged with misdemeanor criminal trespass. Sept. 19, 2002, Comiskey Park: Royals first-base coach Tom Gamboa was assaulted by 34-year-old William Ligue Jr. and his 15-year-old son. The two jump on Gamboa, kicking and punching him until players and coaches from both sides restored order. A folded-up pocket knife was found on the ground afterward. According to the Daily Southtown, Ligue's son spent one month in jail after pleading guilty last October to charges of aggravated battery and mob action. He was sentenced to five years probation, 30 hours of community service and was ordered to undergo counseling. The elder Ligue has pleaded not guilty to the same charges and is seeking the same punishment as his son. May 16, 2000, Wrigley Field: A fan grabbed Dodgers catcher Chad Kreuter's cap, striking him in the back of the head. Kreuter went into the stands after the fan. It took security officials nine minutes to restore order. Nineteen Dodgers players and coaches were suspended. Sept. 28, 1995, Wrigley Field: Cubs reliever Randy Myers was charged by a 27-year-old bond trader who ran out of the stands. The unarmed attacker was knocked down by Myers, who was trained in martial arts, and was arrested. July 13, 1979, Comiskey Park: Bill Veeck's infamous Disco Demolition Night, Fans who brought disco records were allowed into the stadium for 98 cents. The records were to go into a bonfire between games of a doubleheader with the Tigers. About 50,000 fans attended the game and more than 5,000 ended up on the field where a riot ensured. Veeck made futile pleas for the mob to leave. Umpire Dave Phillips called a forfeit, giving Detroit a sweep.

Kansas City GM Allard Baird had told The Kansas City Star that the team will not play Wednesday night's game unless he is satisfied that security at the stadium is improved.

The Royals must be assured "that things have been upgraded where we can feel comfortable to where we can take the field," Baird said. "Otherwise we won't take it. I'm worried about my manager, my staff and my players -- period. But I do feel for the families who came out to the game."

The incident happened just seven months after Kansas City coach Tom Gamboa was assaulted by a father and son who'd run on the same field.

The fan entered the field not far from where Gamboa had been surprised and then pummeled in the first base coach's box last September.

"We spoke about it in the locker room, this is where Tom Gamboa got attacked. We thought nothing was going to happen, but it was a full moon out there," Diaz said.

"He just grabbed me by my waist and that's when I turned him around and got him down ... and everybody jumped on him."

Kevin Hallinan, baseball's senior vice president for security and facilities, flew to Chicago on Wednesday to investigate the incident, ESPN.com's Jayson Stark reports. Hallinan told Stark that he intended to focus initially on what could be done to stop fans from being in position to get onto the field.

"The commissioner has given us carte blanche to get it done," Hallinan told Stark. "That's what's critical here. The White Sox are obviously very, very upset. They work hard. They've got good security people. So we'll huddle with all of them and get right to work."

In a Chicago police report, the fan was identified as Eric Dybas, 24, of Bolingbrook, Ill. He was charged Wednesday with aggravated battery and criminal trespassing.

The Chicago Sun-Times reported he attended the game with a group of five friends and relatives, including Kelly Sherwood, his 20-year-old fiancee. According to Sherwood, as the group entered the park the suspect separated from them. They lost track of him until they saw him on the field, the newspaper reported.

A police spokeswoman said police are leaning toward a charge of aggravated battery, a felony, but that must be approved by the prosecutor's office. The fan's name will not be released until he is formally charged.

Police spokesman Wayne Frisbie said investigators wanted to talk with Diaz before deciding whether to file charges against the man. The assailant, who was treated for minor injuries at St. Anthony's Hospital in Chicago, remained in police custody Wednesday.

Known as Comiskey Park when Gamboa was attacked, the facility is now called U.S. Cellular Field after a $68 million naming rights deal was reached before the season.

As the host for this July's All-Star Game, the stadium has already undergone a major sprucing up. Now it has a black eye, its safety record questioned by yet another ugly incident at a Royals-White Sox game.

	The attorney for the fan who attacked Laz Diaz said his client's stunt was alcohol-motivated.

"As a major league baseball player, you shouldn't have to worry about your health on the baseball field from the fans," Kansas City star Mike Sweeney said. "When they come on the field to do harm, that's when it gets scary."

Immediately after Carlos Lee flied out to end Chicago's eighth inning, a man ran on the field and tried to tackle Diaz.

Security and players rushed to the aid of the 40-year-old Diaz, who served in the U.S. Marine Corps Reserve. The fan was quickly taken away and Diaz, who was not hurt, finished the game.

"When I looked over, there was one of the fans from the stands and I just got him off me," Diaz said. "I just turned around and got him off me. The good hand-to-hand combat they taught me worked."

Several Royals players could be seen kicking and stomping the fan while he was pinned down. When the attacker was put into a police car, his head was wrapped with a white bandage, soaked with blood near the right temple.

Royals right fielder Brandon Berger, who caught the ball for the final out of the inning, was one of the first to reach Diaz.

"You catch the ball, you look down and a guy's getting tackled and it's like, 'What's going on?' " Berger said.

Eerily, it was the first appearance by the Royals in Chicago since Gamboa, then Kansas City's first base coach, was attacked last Sept. 19

Now the Royals' bullpen coach, Gamboa said he thought security was tighter for his team's return. He felt safe -- at least before the game.

"Oh yeah, the assistant to major league security was at the game tonight. He told me before the game that they had beefed up the security, but the fans will always outnumber the security force, so there is only so much they can do," Gamboa said.

"I think people just have too much to drink," he added.

Kevin Hallinan, baseball's security head, was in San Francisco when he learned of the attack. He was on his way to Chicago to investigate.

"I'm going to be meeting with all concerned," he said. "I spoke with Diaz and he did say he thought security got out there in a hurry."

And the attack on Diaz wasn't the only incident involving rowdy spectators. It was just the most brazen.

Earlier, Tuesday night's game was delayed three times when fans ran onto the field before being tackled by security guards. All three were charged with trespassing, the White Sox said.

"The fans just seem to be getting on the field way too easy," Royals third baseman Joe Randa told ESPN Radio. "Guys are getting paranoid and are starting to look over their shoulders. One of the [fans] ran right by me ... I didn't know if he was coming after me or what.

"I don't know if it's the alcohol or if [fans] just want to be on TV. It's got to stop. Hopefully it doesn't happen again, but I guarantee you if something isn't changed with the security, there's a good chance we're not going to play, we're not going to step out on that field."

Frisbie said all three were charged with misdemeanor criminal trespass to land. He identified them as Jeffrey Adams, 25; Albert Skutnik, 25; and Tom Skutnik, 20, all of Chicago.

"I don't know how it is when other teams are in town, but it seems like every time we are here, something crazy happens," Sweeney said. "Maybe they should bring more police in or put up some high fences so fans don't get on the field."

The White Sox said it was the actions of a few who don't represent their true fans.

"The behavior of four people attending tonight's game was reprehensible and will not be tolerated," the team said in a statement. "They will be prosecuted to the fullest extent the law allows."

The 55-year-old Gamboa still has minor hearing loss in his right ear from last year's attack.

The boy, 15 at the time, was sentenced to five years of probation and also ordered to undergo mandatory counseling and perform 30 hours of community service.

He was arrested along with his father, William Ligue Jr., who initially pleaded innocent to charges of aggravated battery and mob action. The case is still pending.

After the attack on Diaz, the Royals scored four runs in the top of the ninth for an 8-5 win -- their 11th victory in 12 games.

Sweeney hit a two-run homer to put the Royals ahead. Albie Lopez (2-0) won and Billy Koch (1-1) lost after blowing the save.

The benches emptied in the first when Miguel Asencio hit Chicago's Frank Thomas with a pitch for the second time this season. No punches were thrown.

Thomas homered in the eighth to give the White Sox a 5-4 lead.

Information from The Associated Press was used in this report.