Iowa exploded for five straight touchdowns bridging halftime, three by star running back Kaleb Johnson and another on Kaden Wetjen’s 85-yard punt return, as the Hawkeyes blew out the Northwestern Wildcats 40-14 in Iowa City, Iowa, on Saturday.

Johnson, who entered the afternoon second in FBS in rushing yards with 1,035, shook off a slow start and amassed 109 yards on 14 carries. He had only 4 yards in his first seven rushes.

Brendan Sullivan replaced Cade McNamara at quarterback for Iowa early in the second quarter to provide a lift. After three straight three-and-out drives, Sullivan and the Hawkeyes engineered a 52-yard scoring drive in just 43 seconds late in the quarter to help Iowa (5-3, 3-2 Big Ten) to a 12-7 lead at halftime. On third-and-1, Johnson found a hole up the middle and went 26 yards for the touchdown.

Sullivan then capped a seven-play, 78-yard drive on Iowa’s first possession of the third quarter, scoring on a 6-yard scamper. Sullivan finished with 79 yards on 9-of-14 passing and 41 yards on eight carries.

When Northwestern (3-5, 1-4) went three-and-out and punted on its first possession of the second half, Wetjen broke to the left sideline and barely managed to stay in bounds before padding the lead to 26-7.

The rout was on when Johnson scored on bursts of 41 and 25 yards inside the last five minutes of the third quarter.

None of the Wildcats’ points came from their offense. In the second quarter, Theran Johnson picked off a pass from McNamara and took it 85 yards for a touchdown and a 7-3 lead. McNamara was pulled after that interception.

In the fourth quarter, Drew Wagner dodged a cluster of defenders after catching a punt and took it 72 yards for a touchdown to make it 40-14.

Iowa, which opened the scoring with a 24-yard field goal by Drew Stevens, also got points from its stifling defense. It happened after punter Rhys Dakin pinned the Wildcats on their 6-yard line. On the next play, Hawkeyes lineman Max Llewellyn sacked quarterback Jack Lausch for a safety, cutting the deficit to 7-5.

Northwestern finished with 163 total yards, while Iowa racked up 355.

Lausch went 10-of-19 passing for 62 yards and two interceptions. Ryan Hilinski completed 5 of 8 passes for 58 yards in relief of Lausch. Cam Porter led Northwestern with 50 yards on 13 rushes.

The Wildcats have lost four of their last five games.