BOSTON—Backup Kain Colter threw for 197 yards and ran for 71 more with a touchdown on Saturday to lead Northwestern to a 24-17 victory over Boston College in the season opener.Colter completed 17 of 24 passes and Northwestern won for the first time since Dan Persa ruptured his Achilles tendon last Nov. 13. Persa, who had been touted as a Heisman Trophy contender by the school, was a late scratch.Andre Williams, who replaced the injured Montel Harris, ran 22 times for 114 yards and two touchdowns. Luke Kuechly had 19 tackles, two for a loss, and an interception for BC,who brought the ball to the NU 19 with 18 seconds left before a false start moved them back and took 10 seconds off the clock. Chase Rettig was sacked by Vince Browne on the final play and remained on the field for several minutes.Ifeanyi Momah caught eight passes for 157 yards for the Eagles, but Nate Freese missed a pair of field goals. Rettig, a sophomore who took over as the started midway through last season, completed 24 of 44 passes for 375 yards with one interception, but he couldn’t find anyone open on the game’s final play.Persa led the nation in completion percentage and total offense last year before he had surgery on a ruptured Achilles tendon Nov. 13; Northwestern lost its final three games, including the TicketCity Bowl. Boston College was without Harris, the Atlantic Coast Conference preseason player of the year.Neither absence seemed like much of a setback.Harris’ replacement, Andre Williams, broke free for 69 yards on the first play from scrimmage. But BC settled for a field goal, and got nothing on its next trip inside the Wildcat 15 when Freese missed a 31-yard field goal.The Eagles made it 10-3 when Kuechly intercepted Colter and ran it back to the Wildcats’ 3 yard-line. After a penalty, Williams scored on a 6-yard run to give BC the lead. Colter tied it when he ran it in himself from 3 yards out to complete a 10-play, 80-yard drive just before the half and then led Northwestern on another just like it to start the second. Mike Trumpy scored on a 5-yard run to give the Wildcats a 17-10 lead, and they went up 24-10 on a perfect option pitch from Colter to Adonis Smith with 9:24 left.Rettig hit Momah for 38 yards to the 2, and two plays later Williams ran it in to make it 24-17 with 6 minutes left. But Northwestern stopped the Eagles on fourth-and-10 with under 3 minutes left, and by the time BC got the ball back there was 1:37 left and they were on their own 36.After an intentional grounding left the Eagles with third-and-16 from their own 30, Rettig brought them to the Northwestern 19 with 18 seconds left. But there was movement before the snap on the left side of the offensive line, resulting in a 5-yard penalty and a mandatory 10 second runoff from the clock.With 4 seconds left, Rettig rolled right but could not get rid of the ball before Browne steamrolled him to end the game.