Lilly, who did not pitch against the Pittsburgh Pirates in the Cubs' 10-8 loss, was checking some of Davidson's calls in the video room.
"I thought both ways, he wasn't concentrating and I asked him if he could concentrate a little bit back there, and he told me he could do whatever he wanted," Lilly said. "That got me upset.
"I became a little upset with the attitude, that he can do whatever he wants because he's the umpire," Lilly said.
The lefty said something to Davidson in the middle of the fifth inning. Lilly couldn't remember if he was tossed, then ran onto the field, or came onto the field and was then ejected. Cubs pitching coach Larry Rothschild and manager Lou Piniella did have to come out of the dugout to step between Lilly and Davidson.
Did Lilly expect to be penalized?
"I don't know what's going to happen," Lilly said. "I hope not. I don't think I was very mean -- I don't remember exactly what I said.
"I'm not going to hold it against him," Lilly said. "Maybe he was doing the best job he could."
Cubs starter Ryan Dempster also did not appear to be happy with some of Davidson's calls -- and his own performance. The Pirates loaded the bases in the third, and Dempster walked two in a row to force in two runs. The Cubs starter took his frustration out on the drink dispenser in the dugout, punching it with his left hand after the inning.
Dempster was pulled after four innings, his shortest outing of the season. He had given up six runs on seven hits and three walks at that point.
The Cubs have lost eight in a row, their longest skid since losing eight from May 2-9, 2006.
"I don't think we're going to take it out on umpires," Lilly said. "We're not losing games because of them. That's pretty simple."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.