Posted by ESPN.com's Adam Rittenberg
A seed of doubt crept into Adrian Clayborn's mind as Arizona lined up for first-and-goal at the Iowa 1-yard line in a Sept. 19 game. The odds favored an offensive touchdown. Most likely a rushing touchdown.
What came next? A Nic Grigsby run for a loss of two yards followed by two incomplete passes. Field goal. Thanks for playing.
Surely the streak would end two weeks later at Penn State, as the Nittany Lions entered Iowa territory five times. Penn State never got closer than the 11-yard line and wound up with only one Collin Wagner field goal.
"They had us back down in the red zone and we came up big with stops," said Clayborn, Iowa's star junior defensive end.
At least Penn State running back Evan Royster knows what it feels like to notch a rushing touchdown against the Hawkeyes. He had a 2-yard scoring run in the second quarter of last year's game in Iowa City. One quarter later, his teammate Derrick Williams ran one in from nine yards out.
Since then? Nothing.
Iowa has painted its own goal line in black and gold. If an opponent wishes to cross it, they had better not try on the ground.
The Hawkeyes haven't allowed a rushing touchdown for 33 consecutive quarters, the final 13 last season and the first 20 of 2009. The amazing streak epitomizes a defense that ranks 10th nationally in points allowed (13.4 ppg) and is the biggest reason for Iowa's first 5-0 start since 1995.
Iowa puts its streak on the line Saturday night when its hosts Michigan at Kinnick Stadium (ABC, 8 p.m. ET).
"It’s astounding," Michigan head coach Rich Rodriguez said. "Normally, you maybe get a quarterback sneak or something in the goal line where you get in there. To have 33 straight quarters, an eight- or nine-game span, is really quite remarkable."
Hawkeyes head coach Kirk Ferentz added, "I’m not a good one on streaks and records, but I know this: it’s a good thing."
The streak might be the flashiest thing about Iowa's defensive line, and predictably, players barely spend any time discussing it. Iowa's D-line isn't defined by streaks or schemes or individuals, but by flawless fundamentals, versatile players and a relentlessness that opponents can't match for 60 minutes.
"They fight every play, as long as it lasts," Hawkeyes linebacker Pat Angerer said. "They bring so much intensity to the game."
Trying to pinpoint why the Hawkeyes' front four is so effective can be a futile endeavor.
"We’re just playing our Iowa defense and trying to stop people," Clayborn explains. "As the game goes on, we tend to play hard and play faster."
Their Iowa defense, implemented by veteran coordinator Norm Parker, contains few tricks or surprises. Linemen fill their gaps, explode off the snap and remain technically sound.
No frills. Not many yards or points, either.
"They don’t give up hardly any big plays," Rodriguez said. "You have to earn everything.”
Iowa's defense has survived on simplicity for years, producing star linemen like Aaron Kampman, Colin Cole, Matt Roth and Jonathan Babineaux. But the line appeared headed for a drop-off this fall.
Defensive tackles Mitch King and Matt Kroul, both four-year starters, exhausted their eligibility, leaving two major holes in the middle of the defensive line.
To combat the losses, Christian Ballard moved inside after starting opposite Clayborn at defensive end last fall. That cleared the way for end Broderick Binns, who had stood out during spring practice and continued his development during preseason camp.
Clayborn and Binns have combined for 7.5 tackles for loss, 4.5 sacks, four pass breakups, eight quarterback hurries, three forced fumbles and two blocked kicks. They accounted for nine of Iowa's 21 points in the win at Penn State, as Binns forced a fumble that resulted in a safety and Clayborn blocked a punt and returned it to the end zone.
Karl Klug has filled King's role at defensive tackle with 6.5 tackles for loss, 2.5 sacks and a forced fumble.
"Christian did a good job of moving inside and taking one for the team," Clayborn said. "We’re just team players.”
Ferentz calls the 2004 D-line -- which consists of ends Roth and Derreck Robinson, and tackles Babineaux and Tyler Luebke -- the best group he's coached at Iowa. But the current unit could be catching up.
"The good news is this group can improve a lot," Ferentz said. "Hopefully, they’ll keep getting better as the year goes along."