SYRAC– USE—Backup quarterback Trevor Siemian hit Demetrius Fields for a 9-yard touchdown pass with 44 seconds left and Northwestern held on to beat Syracuse 42-41 Saturday in the teams’ season opener.Siemian, subbing for starter Kain Colter, drove the Wildcats 75 yards in 10 plays, taking advantage of a critical personal foul against Syracuse defender Keon Lyn for a late hit out of bounds on the previous play.The decisive score in the sweltering Carrier Dome came after Ryan Nassib had engineered a stunning comeback for the Orange, throwing for four second-half touchdowns. Nassib finished 44 of 65 for 470 yards. His completions obliterated the school record of 29 he’d shared with Marvin Graves and Andrew Robinson.Nassib threw a pretty 20-yard TD to Christopher Clark in the left corner of the end zone with 2:40 left in the game for the go-ahead score with 2:40 left and Prince-Tyson Gulley ran in the two-point conversion to give the Orange a 41-35 lead after having trailed 35-13 in the third quarter.Nassib also hit Marcus Sales for a 7-yard touchdown and combined with Jeremiah Kobena on scores of 50 and 7 yards, the latter with 6:42 left in the fourth to move Syracuse within 35-33.Syracuse was still in it at halftime despite the heroics of Northwestern star Venric Mark, who scored twice and accumulated 203 all-purpose yards in the first half. The Wildcats have their Home opener against Vanderbilt next Saturday night.