Four-time Pro Bowler and Cardinals newcomer Joey Porter also got in the face of fellow outside linebacker Cody Brown for putting up with tight end Stephen Spach repeatedly grabbing Brown's facemask in the drills.
It was the first practice in full pads for the Cardinals and the third straight workout forced by rain indoors to the Northern Arizona University's domed stadium.
Dockett was on top of guard Alan Faneca and reached out to trip quarterback Matt Leinart, who slammed the ball down in disgust. Brown faced off with Dockett in a shoving match before the two were separated.
Coach Ken Whisenhunt didn't mind the intensity at all.
"It was nice to see guys getting after it," he said, "but that's typical of being in full pads the first day. The emotions were running high."
Dockett and Whisenhunt were pleased to see some fire from the normally low-key Levi Brown, who is being switched from right to left tackle.
"I'm proud of him," Dockett said. "That's what I expect him to do. I pat him on his back and at the end of the day that's my child, that's my family."
Whisenhunt called Brown's reaction "a good thing."
"You're looking for guys to develop that bond or that kind of territorialism to protect their guy," the coach said, "and that was good."
Dockett said he pushed Faneca back and fell on him.
It was the second day in a row that Dockett had knocked Leinart down.
"I swiped my hand and hit Matt in the ankles," Dockett said. "That was kind of dumb. I shouldn't have done that. But you get caught in the battle, the engine turns on, you really don't think about it until after the fact."
Porter wasn't pleased with what he saw as a passive reaction by Cody Brown, a second-round draft pick a year ago who missed all of last season after breaking a wrist in training camp. Porter said if a player puts up with that in camp, he will do it in a game.
Dockett said that's one reason he loves having Porter around.
"That's what its all about, it's all about attitude,'" Dockett said, "much as you love your teammates, damn, you're trying to kill them."
He said he's just trying to give maximum effort as an example.
"You can't come out here and go 80 percent and expect to win our third divisional title," Dockett said. "It just don't happen like that. Every day we step on the field we've got to go harder and harder and harder. We've got to treat them like they're the 49ers and they've got to treat us like we're the 49ers. That's the only way we're going to be able to compete."