Tyrell Johnson has thought about this first game for awhile, played it over in his head quite a few times. And he’s done pretty well, in his mind.

“About two interceptions and 20 tackles,” he said, cracking a smile.

Johnson, the team’s top draft choice, will play in his first professional game when the Minnesota Vikings host Seattle at 7 p.m. today at Metrodome. He’ll likely play quite a bit as a reserve safety, and he’s been put on all phases of special teams.

“I’m excited, ready to show what I can do,” he said. “I’ll do my best.”

Johnson, who was chosen in the second round with the 43rd overall pick, has been flattened by veterans, as he was by Larry Johnson in a recent practice with Kansas City, and he’s been beaten deep by receivers, as he was on a couple of passes this week.

“That’s a rookie thing, everybody makes mistakes,” Johnson said. “You have to shake it off and make the next play. Tough-minded, you have to be tough-minded.”

Coach Brad Childress said that Johnson has done a good job of battling through the camp aches and pains, showing up ready to work at each practice.

“He’s shown the ability to hit, he seems to be a quick study,” Childress said. “I want to see how that stuff transfers (from practice to games.)”

Johnson said he feels like he’s having a good camp, and starting safety Darren Sharper agrees.

“He’s what everyone said he was, an athletic safety,” Sharper said. “He’s a good, hard worker who wants to learn. That’s the kind of kid you want to teach.”

Now, it’s time for Johnson to play like he’s been practicing.

“I know what I can do, I just have to stay focused,” he said. “I want to take my game to a new level.”

Notes

Childress said the starters will play at least the first quarter, though he reserved the right to change that plan, depending on the number of plays each unit gets. “We have a plan, but don’t tie me to it,” he said. He plans to use all four quarterback, starting with Tarvaris Jackson and following with Gus Frerotte, Brooks Bollinger and John David Booty. ... Defensive end Brian Robison (calf), cornerback Marcus McCauley (knee) and tight end Garrett Mills (ankle) will not play tonight. ... The Vikings went through a 90-minute walkthrough Thursday, which was closed to the public, working on situational things and “crazy” plays. The team held meetings Thursday night and again this morning before traveling to the Twin Cities. The players have an off day Saturday, and the next practice is scheduled for 3 p.m. Sunday. ... Sharper’s reaction to the trade that sent Brett Favre from Green Bay to the New York Jets: “I love playing against him. I would have loved for him to stay in the NFC.” Added kicker Ryan Longwell, on the provision included in the trade that likely prevents the Jets from trading Favre to the Vikings: “Three No. 1 picks is certainly imposing. That’s the definition of poison pill.”