WEST LAFAYETTE, Ind. -- On a day when starting quarterback Trevor Siemian was lost in the second quarter with a left knee injury, Northwestern's defense and special teams compensated, producing a much-needed victory.

Linebacker Jimmy Hall set up 14 points with an interception and a fumble recovery, and the Wildcats beat Purdue 38-14 on Saturday.

"I was just at the right place at the right time, really," Hall said of the two plays that established the early momentum. "It was just guys stepping up, getting forced fumbles, and I was just there at the right time."

Purdue finished with five turnovers.

A victory against Illinois on Nov. 29 would make the Wildcats (5-6, 3-4 Big Ten) bowl eligible. Northwestern last week upset Notre Dame 43-40 in overtime, snapping a four-game losing streak.

Siemian hurt his left knee trying to pick up a first down and did not return. He was replaced by Zach Oliver. Coach Pat Fitzgerald said the knee injury appears to be a serious one, although he won't know specifics until after tests are run.

"We have had a lot of injuries, but our young men have persevered," Fitzgerald said. "They've kept on battling, and obviously, our backs are against the wall one more time next Saturday."

Replacing Siemian was difficult emotionally for Oliver.

"Trevor and I are best friends, so it's tough," said Oliver, who completed 5 of 11 passes for 85 yards. "We have to move on. We still have a win to get next week, and then a bowl win, and we are going to be playing for him. Coach Fitzgerald has been calling this little final streak our playoffs, so we have to get that W against Illinois."

Hall's interception of a pass by Austin Appleby -- one of four first-half Purdue turnovers -- set up Northwestern's first score, a 24-yard pass from Siemian to Dan Vitale.

Hall recovered a fumble by Akeem Hunt at the Northwestern 43, setting up a nine-play, 57-yard drive, capped by Justin Jackson's 9-yard touchdown run for a 14-0 lead.

Jackson finished with 23 carries for 147 yards and two touchdowns.

Purdue (3-8, 1-6) has yet to win a Big Ten home game in coach Darrell Hazell's two seasons, falling to 0-8.

The Wildcats took a 21-0 lead with 14:07 left in the second quarter when Tony Jones returned a short punt 64 yards for a score. It was the first time since the 2008 season that a Purdue opponent returned a punt for a touchdown.

"The punt was a line drive, and it was coming straight to me," Jones said. "I knew regardless whether or not I caught it that guys were going to be around, so I felt like I had enough time to go make a play. From there, it was just great blocking, I'm old and slow now. I have to credit guys for providing great protection for me."

Northwestern defensive end Deonte Gibson recovered a fumble by Appleby at the Purdue 18 with 4:15 remaining in the second quarter, setting up a 32-yard field goal by Jack Mitchell that gave the Wildcats a 24-0 lead.

Purdue drove 75 yards in 12 plays to pull within 24-7 with 37 seconds left in the first half, scoring on a 19-yard pass from Appleby to Hunt. Appleby added a second touchdown pass in the game's final minute to account for the final score.

Northwestern dominated the first half statistically, running 50 plays for 242 yards, while Purdue's 39 plays produced only 129 yards. Appleby threw an interception and a lost fumble during the first 30 minutes, and Hunt lost two fumbles in the first two quarters.

Before being injured, Siemian completed 7 of 12 passes for 93 yards and one touchdown. He also was intercepted once.

Purdue had the ball for 9:45 during the third quarter and missed a field goal when Paul Griggs' 42-yard attempt bounced off the left upright.

Northwestern took a 31-7 lead with 14:06 remaining in the fourth quarter, getting a 1-yard touchdown run from Tim Hanrahan.

Jackson got his second touchdown of the day with a 68-yard run off right tackle with 9:14 to play, pushing the lead to 38-7.

The defeat extends Purdue's losing streak to five. The Boilermakers have not won since beating Illinois 38-27 on Oct. 4 in Champaign, Illinois.

"We turned the ball over four times in the first half, and we are just not in a situation right now to dig ourselves a hole that deep and overcome that," Hazell said. "We're not doing a good enough job catching and throwing. We have to do a better job executing the simple things."

Purdue leads the all-time series against Northwestern, 50-28-1.