MANKATO, Minn. (AP) _ Minnesota Vikings defensive tackle Pat Williams' rotund frame has always been a punch line. Listed at 317 pounds in the team media guide, jokes like, ``You mean his high school media guide?'' have become common around here. No one is laughing now.

One of the leaders of the Vikings' defense has missed the first three days of training camp because of weight and conditioning issues, and defensive coordinator Mike Tomlin called the situation ``disappointing'' on Wednesday.

With temperatures soaring early in the week, Williams was placed on the active physically unable to perform list after showing up to camp a few pounds overweight and slightly out of shape. But even after heavy rain cooled things off, Williams still was not in uniform.

Coach Brad Childress has reasons to be cautious. He was coaching in Philadelphia five years ago on the day when massive Vikings tackle Korey Stringer collapsed in the sweltering heat in Mankato. Stringer's heatstroke death cast a pall over the franchise and prompted every team to examine how it conducts training camp.

``He isn't where he needs to be,'' Tomlin said bluntly. ``It's disappointing for me, it's disappointing for his teammates, it's disappointing for him. We've got one standard here in physical conditioning, in preseason and in anything else. As of right now, he's not up to snuff so he's got some work to do.''

Williams, who struggled in a conditioning test on Monday but did not appear to be much heavier than he usually is, declined an interview request.

Coming off a career season in which he narrowly missed the Pro Bowl, the Vikings need Williams to be the run-stuffing nose tackle in Tomlin's new ``Tampa 2'' defense. Tomlin, the former secondary coach in Tampa Bay, envisions Williams as the Vikings' version of Booger McFarland _ a disruptive, athletic and powerful force in the middle.

Williams showed he could be just that last season. Playing closer to 340 pounds didn't keep the 10-year veteran from running sideline-to-sideline to chase down running backs, quarterbacks and sometimes even receivers.

He has dealt with weight issues his entire career, and most of his teammates didn't think Williams would have much trouble getting things under control.

``Pat's doing real good,'' cornerback Fred Smoot said. ``They're just trying to take special precautions, make sure everything's good. Nothing's actually big about the situation.''

Nothing, that is, except for ``Big Pat.'' His teammates endearingly gave the jovial Williams that moniker, though it refers more to his play on the field than the reading on the scale.

More than just a hole-plugger who gobbles up blocks to free up his teammates, Williams led all Vikings defensive linemen with 88 tackles and nine tackles for loss last season.

Perhaps that's why Tomlin was so pointed in his remarks on Wednesday _ he knows how important Williams is to the success of his defense, which is predicated on the front four putting pressure on the quarterback and stopping the run.

Playing alongside former All-Pro Kevin Williams, Tomlin thinks the two friends can create the kind of havoc on the interior that McFarland and Warren Sapp did for so many years in Tampa.

Tomlin didn't set a timeline for Pat Williams' return, saying ``that will be determined based on his progress.''

Childress was a little less pointed earlier in the week, when he first placed Williams on the active PUP list, which means he cannot practice or workout with the team.

``He had done just a great job. He had lost 14 or 15 pounds in the offseason, steady coming down, and it got away from him,'' Childress said. ``He's as disappointed as I am. You've got to make that call and he's going to have to spend some time here and pull it back together.''

When Pat Williams does get back, everyone better watch out.

``Pat's hungry to get out here,'' Smoot said, pardon the pun. ``He wants to get him a piece.''