Freshman Grant Gunnell threw for 352 yards and a touchdown in his first career start, playing in place of injured Khalil Tate, to lead Arizona to a 20-17 win over UCLA in a Pac-12 game Saturday night.

Tate did not play because of a hamstring injury suffered at the end of the previous game against Texas Tech two weeks ago.

UCLA's J.J. Molson missed a 39-yard field goal wide right with 34 seconds left that could have tied the game.

The Bruins were led by Joshua Kelley's 127 yards on 27 carries with a touchdown.

Gunnell completed 29 of 44 pass attempts and 182 of his passing yards were in the second half when Arizona outscored UCLA 14-10.

He completed a pass on a third-and-9 play at the Arizona 7 with 6:00 left in the fourth quarter to keep the drive alive. It later appeared that he connected with Brian Casteel on a 42-yard touchdown pass but a review showed Casteel's left knee touched the ground when he made the completion 2 yards behind the line.

Arizona eventually had to punt and UCLA gained possession on its 9 with 2:52 remaining. UCLA backup quarterback Austin Burton, playing in place of injured Dorian Thompson-Robinson (ankle), guided the Bruins to the Arizona 21, setting up the failed attempt by Molson.

UCLA continued its momentum from the previous week, when it rallied from 32 points down to upset Washington State at Pullman, Wash., by driving 85 yards on 12 plays for a touchdown on its first possession.

The Bruins scored on a 2-yard pass from Thompson-Robinson to Matt Lynch with 8:33 left in the first quarter. Thompson-Robinson rushed for 40 yards on two carries in the drive. UCLA, which led 7-6 at halftime, sputtered after that first scoring drive, gaining only 100 more yards in the half.

The Bruins opened the second half with a 37-yard field goal by Molson, capping a 17-play drive that went 56 yards.

On Arizona's first play of the ensuing possession, Gunnell connected with a wide-open Darrius Smith for a 75-yard touchdown pass, giving the Wildcats their first lead, 13-10 with 8:17 left in the third quarter.

Thompson-Robinson exited the game because of an ankle injury with 50 seconds left in the third quarter. He completed 17 of 33 passes for 180 yards with a touchdown and interception. He also rushed for 63 yards on nine carries.

Burton completed 5 of 9 passes for 48 yards.

Kelley rushed 36 yards on the next play and then scored on a 3-yard run with 2 seconds left in the quarter to put UCLA ahead 17-13.

Arizona converted a critical fourth-and-1 play with Gary Brightwell getting that one yard to the Arizona 48 with 12:25 left in regulation. Gunnell completed three consecutive passes for 42 yards before Brightwell ran into the end zone from 10 yards for the score to give Arizona a 20-17 lead with 10:51 left.

--Field Level Media