Purdue knew its defense would bend at times against the country's No. 1 passing offense.

But what it wanted to do was occasionally break Marshall, and it did with three critical second-quarter interceptions that turned the tide toward the Boilermakers. The three picks, the latter two returned for touchdowns, helped Purdue (3-1) to a 28-point halftime lead in an eventual 51-41 victory.

Antoine Lewis, probably Purdue's No. 5 cornerback on the depth chart, got the turnover trend started when he picked off a bobbled ball for his first career interception. The Boilermakers later scored on the ensuing drive, giving them a 28-14 lead.

"I think that was the change in the game," junior corner Ricardo Allen said of Lewis' pick. "Our D-line got a little hyped, they started to get a little pressure on the quarterback and he started making mistakes."

The Thundering Herd's next two drives also ended in interceptions, with Allen taking the first back 39 yards for a score and Josh Johnson taking his 74 yards to the house. In only minutes, Purdue had turned a seven-point lead into a 28-point edge.

"Any time you get two pick-sixes in the first half and have that kind of cushion at halftime, I think that's huge for your football team," Coach Danny Hope said.

Marshall got its yardage. The Thundering Herd, which had been averaging more than 370 yards passing behind quarterback Rakeem Cato and had 334 yards rushing last week, finished with 543 yards in 91 plays.

"We knew during the week that they were going to pass for a whole lot of yards," Lewis said. "They're a great passing offense. So I felt like getting them off the field, via takeaways, was huge. Me getting the first, everyone on the defense felt a lot of momentum, and it's infectious."

Gary Bush had endured a rough couple of weeks, with his confidence hitting a low as the opportunities for receptions dwindled.

The junior receiver had only three receptions for 11 yards in the last two outings, after a six-catch, one-touchdown season debut. But Bush took advantage of the bye week, going home to Miami for a few days to mentally reload.

Bush says he came back Sunday, the first day after a three-day break from practice, feeling refreshed.

"It was kind of frustrating," Bush said, "but I went back home and tried to think about the team, instead of thinking of myself. My mother and everybody talked to me.

"I was able to clear out my head."

It worked. Bush rebounded with career-highs of seven catches for 83 yards and three touchdowns.

"It shows that hard work pays off," he said.

Purdue went to Bush early, as was the game plan, to try to get him started. On the Boilers' first pass, Bush caught a six-yarder. The drive ended with him hauling in a nine-yard touchdown grab. He added a 35-yard jailbreak screen for a score, which followed Lewis' interception in the second quarter, and was responsible for the crucial third-down catch that gave Purdue a 51-35 lead with under seven minutes left.

"We wanted to get the ball in his hands early to create some confidence for Gary," Hope said. "Him scoring early in the ball game was big for him. ... It was good to see him step up and make plays."

Purdue's third quarter woes, which started last season, kept up on Saturday.

The Boilers were outscored 14-3 in the third - and Marshall scored another TD two minutes into the fourth - bringing the Herd to within 10.

Afterward, Hope said the Boilermakers would like to find the ability to put teams away.

"We would have liked to have taken that step today," he said. "That was our challenge to our team at halftime. Yes, we are disappointed that we didn't put the game away early in the third quarter."

Purdue had the ball to start the third, but went three-and-out. Its second drive ended with a Caleb TerBush interception after he threw into coverage while under pressure. The third was another three-and-out, which ended in a blocked punt for touchdown.

TerBush was at a loss to pinpoint the problem.

"I couldn't really tell you right now," he said. "We'll go to the film and see if we can pick some things out. It's little things; we're right there. And once we iron those out, we should be all right."

Hope made the issue a priority during training camp, trying to change the approach used at halftime to spur better third-quarter starts. This season, the Boilers have re-stretched after exiting the locker room at the half, but it hasn't worked to solve the third-quarter sluggishness.

Purdue struggled starting the third vs. Notre Dame and did so again vs. the Herd.

"I don't think it's a curse or a jinx," Hope said. "I think it boils down to some sort of execution issue. That'd be my gut feeling on it; we've got to play a bit better in the third quarter."

Allen might want to make sure his mother, Brenda Green, can attend as many games as possible.

In each Purdue game she's attended - and she was in the stands Saturday, traveling from Daytona, Fla. - Allen's had an interception. And twice, he's returned them for a score.

"So I think she needs to travel a little more," Allen said with a smile. "... I said (to her) 'If you want me to go first round (in the NFL Draft), you've got to come to the games."

The pick-six was the fourth of Allen's Purdue career, breaking the all-time school mark previous held by Hall of Fame DB Rod Woodson and former linebacker Mike Rose.

"He played well and he was challenged some with the quality of player that they have," Hope said, "but he's a great competitor and plays with a lot of emotion."

On his pick, Allen says he recognized the play and was able to jump the route. Pressure from Robert Maci, who had hit Cato on the backside on the delivery helped.

Allen quickly reversed course, and had a path to the end zone, as long as he didn't run into too many of his own players.

"We practice that a lot," he said. "It's called 'Up-the-numbers.' Coach (Tim) Tibesar does a great job with it. Probably last year, everybody would have turned around and bumped in to you. But this year, we have a drill and every time an offensive player drops a ball, we have to run up the numbers (to create a path). It turned out to be a good thing."

Purdue is 3-1 in the nonconference for the first time since 2007, when it started 5-0.

The Boilermakers have avoided a bad out-of-conference loss, like the ones they had vs. Northern Illinois, Toledo and Rice over the last three seasons.

"We're 3-1 and even more important than that we're 3-0 in Ross-Ade," Hope said. "That's one of the goals for our football team this year is to go undefeated in Ross-Ade Stadium. That would be huge for our team and program. We feel like if we can go undefeated in Ross-Ade, we'll be in good position to compete for the Leaders Division."

Purdue's happy to be where it is now, with the Big Ten season starting next week.

"Not losing to a MAC school is one thing, being undefeated at home is another," Maci said. "We've got Michigan next week and we're looking forward to being at the top of our division if we beat them."

Purdue committed nine penalties for 80 yards against Marshall. But of the nine, four were personal fouls.

One was charged to offensive lineman Peters Drey, for a block on an unsuspecting defender; another was called on Gabe Holmes for a late hit; a third on Taylor Richards for a hit out-of-bounds; and a fourth on Kawann Short after hitting Cato late on a fourth down.

"We'll look and see how they came about," Hope said. "We had one on a late hit on the quarterback that I thought was awfully close. And we had one where we hit a guy too far out of bounds and that was probably a poor decision. But we'll look and see on film.

"But we came into the game as the least penalized team in the Big Ten and plan to continue our pursuit of being the most disciplined football team."

Short picked up yet another blocked field goal, the fifth of his career, to go with two other extra points he's put away.

The block was his third of the season.

Short nearly had another block. On Marshall's first extra point attempt, he and Bruce Gaston nearly their hands on the ball.

"Jogging off the field, we knew we could get it," he said. "It's all based on that first push we get in the game. We probably should have gotten that one. I needed to jump a little higher; I don't think my vertical is that good."

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