The Bears' celebration of their pending 100th anniversary season carried on Saturday with a crowd of its most devoted fans estimated by the team to be between 8,000 and 10,000.

After a visit with Jim McMahon and Mitch Trubisky to kick off Saturday’s festivities, fans suffered their first real disappointment of the weekend after Brian Urlacher was forced to cancel his appearance with fellow Hall of Fame MLBs Dick Butkus and Mike Singletary due to illness.

Fortunately, few can entertain and hold a crowd’s attention the way Butkus can, and together he and Singletary gave the fans an hour that was one of the highlights of the day.

For all the stories of Butkus’ up-and-down relationship with Papa Bear George Halas over contract negotiations, many in the crowd were moved when he shared his deepest feelings about one of the NFL’s founders.

“My first impression with George Halas was, for me, was I’ve reached the ultimate.

“I thought, how could anybody who’s playing football not want to play for this guy? Here’s the guy sitting here that started it all. So, I was blessed.

“I don’t care how much money I would have made somewhere else. It was, for me, to play for this guy who started the league, was something else because that was my life at the time.”

Singletary didn’t get to spend a lot of time around Halas but did display those Samurai eyes when asked about his introduction to Mike Ditka.

“I was so excited the first time he (Ditka) walked in the room and I had no idea who coach Ditka was. I just heard the guys talking about him. The first thing I heard was kind of alarming. Someone said ‘Who did they hire? They hired Ditka, oh my goodness, we don’t want this guy, he’s crazy.’

“I don’t know how George Halas coached, but I can imagine that the fire and intensity and passion that Coach Ditka exuded that first day set the tone for exactly what he said, three years from now we’re going to be in the Super Bowl and that was 1982. In ’85, we were there.”

Ditka is still recovering from surgery after a serious heart attack at the beginning of the year but looks good and was in full Ditka form — although he did surprisingly offer one mea culpa for his behavior in the ‘80s and ‘90s.

“I was nuts. I was a pain in the ass," he said. I was out of touch with reality for 20 years. Now I’m a pretty good guy.

The main hall of the convention center was near capacity for back-to-back panels first with 2006 NFC Champion Bears Olin Kreutz, Roberto Garza, Patrick Mannelly, Devin Hester and Charles “Peanut” Tillman and then a visit with “The Safeties,” Gary Fencik, Doug Plank, Mike Brown and Eddie Jackson, and it was number 46 (Plank) who stole the show.

Plank described his style as wanting to be “the Dick Butkus of safeties,” and said that he would prepare for games all week long convincing himself the backs and receivers he would be facing Sunday “had just beaten his wife and his mother and it was time for payback.”

If you had to pick one moment of the day, it had to be Butkus talking about his teammate, Doug Atkins.

“Doug Atkins was probably the closest man to Superman.

“He never worked out, and you know the funny thing, he used to tip that Tennessee Whiskey a little bit.

“So, Halas never said much but then the expansion comes and Doug ends up in New Orleans.

“Doug quits drinking, he starts working out, he’s having a Pro Bowl year and he says, I’m going to keep playing until I get a crack at the Bears.

“Randy Jackson was the tackle that would have been over him and he was shi - - -g a gold brick all week long, ‘Damn, I’ve got to try and block Atkins . . .’

“He was without a doubt the closest thing to Superman, stronger than all get out and he never did anything.

“They claimed one night before a game he had 36 martinis and two cases of beer, and I believe it.”