If Oregon State didn't know yet what it had in its defense, the Beavers learned on the third play of the third series of the season.

Facing third-and-one at its own 33-yard line, Wisconsin handed the ball to 2011 Heisman Trophy finalist Montee Ball.

Running a version of "Power," the 5-foot-11, 215-pound senior surged up the middle and to the right.

The Beavers blew Wisconsin off the line of scrimmage, knocking right guard Zac Matthias down.

Sophomore linebacker D.J. Welch smacked Ball to the ground for no gain.

"We stuffed it," said Welch, who was named Pac-12 Defensive Player of the Week for his Week 1 effort. "That was an all-time best moment."

The No. 13 Badgers went on to go 2 for 14 on first-down chances, and lost 10-7 after gaining 35 yards on 23 rushing attempts.

"That play," junior linebacker Michael Doctor said, "did set the tone for us that game."

It carried over to the next one, too, when OSU held Johnathan Franklin, then the nation's leading rusher, to 45 yards on 12 carries.

The Beavers beat No. 19 UCLA, 27-20, marking the first time in 12 years OSU had topped ranked teams in back-to-back games. They will play their third game of the season Saturday at Arizona Stadium, riding what, at least so far, has been one of the nation's most remarkable turnarounds.

Last season, Oregon State was No. 101 in the nation in rush defense, allowing 196.8 yards per game.

This year, the Beavers are No. 2 nationally, allowing an average of 53.5.

Against UCLA, the Beavers played their typical 4-3 front with quarters coverage, allowing the safeties to aggressively pursue the running back.

On passes, OSU played zone coverage with, to quote basketball announcer Bill Raftery, man-to-man principles.

"Everybody's feeling pretty good - especially stopping those two running backs," said Doctor, who is second on the team with 12 tackles. "I think a key to it was everybody flying around to the ball, and having a lot of want-to.

"You have to be physical."

Experience helps, too. While the Beavers trudged through a 3-9 season last year, they played a school-record 10 true freshmen.

This year, both the team's starting defensive ends and both starting safeties are sophomores.

"I think it's confidence as much as anything," OSU coach Mike Riley said. "A lot of those guys played their first (college) football last year.

"They got a taste of what it was like."

Stellar run defense has helped Oregon State succeed on what become long passing downs, Riley said.

Opponents have completed only 4 of 29 third-down attempts, the lowest percentage in America.

That's why, despite collecting only one turnover this season, the Beavers are No. 18 in the nation with 13.5 points allowed.

Of the teams ahead of OSU on the list, none has, as the Beavers have done, played exclusively Bowl Championship Series opponents. (OSU's opener with Nicholls State was rescheduled after a hurricane.)

UA coach Rich Rodriguez said that "it looks like they really understand" what defensive coordinator Mark Banker teaches.

The Beavers figure to spy UA quarterback Matt Scott with Doctor, who kept an eye on UCLA's Brett Hundley last week.

"They've got good secondary players, some of the best in the country, but they're really strong up front," Rodriguez said.

"They roll with a lot of guys. They've got great size.

"They give great effort."

OSU insists it has work to do, even if the early returns have been dominant.

"We just carried through the first game to the next game," Welch said. "We kept going, and we kept building."

By the numbers

A look at Oregon State's surprisingly dominant defense:


The Beavers are No. 1 in the country, having allowed opponents to convert 13.79 of their third-down attempts.


OSU is second nationally in rush defense, allowing 53.5 yards per game.


Points allowed per game by OSU, No. 18 in the country.


Rank in total defense for OSU, allowing 325.5 yards per game