The formula for going on the road and knocking off a ranked team requires two important ingredients: Make some big plays and avoid allowing big plays.

UNLV couldn't do either in Saturday night's game at Rice-Eccles Stadium in Salt Lake City against No. 22 Utah, particularly in the second half as the Utes ran away with the 42-21 win in the Mountain West Conference opener for both sides.

"We got some things clicking and got some momentum," Utah head coach Kyle Whittingham said. "When you get the momentum especially at home, things seem to snowball."

The Rebels started out strong, going in front 7-0 and 14-7 on a pair of short Frank Summers touchdown runs in the opening half and things might've been even better for the visitors if some plays in the second quarter had gone their way.

The biggest shift in momentum came only a few minutes before the half when UNLV -- which led by seven at that point -- appeared to have stripped Utah running back Darrell Mack and recovered the fumble near midfield.

After the play went up to the replay booth, however, the MWC referees decided that Mack's knee had touched the ground before the fumble and gave the ball back to the Utes.

Utah -- revitalized by the decision -- drove the ball down the field and tied the score with less than a minute to play with running back Matt Asiata plowing into the end zone from two yards out.

"We knew we needed to put some points on the board at that point," said Ute wide receiver Freddie Brown. "After that we were able to do that and tie things up."

It was one of two fumbles that the Rebels were unable to get, the second coming in the third quarter when three UNLV players had chances to get another Mack fumble but Utah tight end Colt Sampson somehow managed to get there first.

"We can't put the ball on the ground," said Ute quarterback Brian Johnson. "We were fortunate to recover them tonight but we can't do that."

The Asiata score right before the break helped Utah get things going.

"It was a tight game at the half and we were fortunate to be tied," Whittingham said. "It was very important for us to come out on the first drive of the second half and stick it in the end zone."

The inconsistent Ute offense got a big boost to start the third quarter as returner David Reed broke free and returned the kickoff out to near midfield, although he had to hear it from his teammates because he got tackled by Rebel kicker Ben Jaekle.

"I was thinking too much," Reed said. "I tried an in-and-out move but I was too slow. It won't happen again."

That sparked the home team as Utah moved in and scored to take the lead for good on a 32-yard pass from Johnson to Brown.

The Ute defense, which had allowed Summers to gain 82 yards in the first half, came out determined to make a stand and succeeded as they forced UNLV to go three plays and punt.

Utah punt returner John Peel kept the momentum building by bringing the kick back 25 yards, giving his team another short field.

"Peel and Reed both played very well and were very dangerous," Whittingham said. "Our return game was much improved this week."

The Utes punched the ball in on a reverse to Reed, who scored his first career touchdown for Utah from 15 yards out and the rout was on.

The home team added another touchdown in third quarter, an 8-yard pass from Johnson to Sampson, then finished its scoring on a 32-yard play-action pass from Asiata to receiver Jereme Brooks.

UNLV added a 10-yard touchdown pass from quarterback Omar Clayton to wide receiver Phillip Payne with just over six minutes left in the game, but Utah proceeded to run out the clock on its next drive.

"I don't know why it took us until the second half to wake up offensively but it did," Whittingham said. "Our defense played well throughout the game and our special teams had another positive night."

The defense only allowed Summers to run for five yards in the second half but he only had five carries as the deficit forced the Rebels into more passes.

Johnson had a solid game for the Utes, leading the team with 183 yards and two touchdowns passing on 15-of-24 attempts with one interception. He also totalled 80 yards on the ground, including a 56-yard touchdown run in the second quarter that started the Utes' scoring.

Utah heads to Logan next weekend to take on Utah State while UNLV has another tough road game at Arizona State.

• Notes: Six different players scored touchdowns for Utah, including the first scores ever for Asiata, Brown and Reed ... Stevenson Sylvester led the Utes on defense with nine total tackles ... Utah scored touchdowns on all four third-quarter possessions as its average start position was the UNLV 46.5-yard line ... Ute kicker Louis Sakoda scored his 200th point with a point-after touchdown in the first quarter. He has 205 total points in his career ... the announced attendance was 45,587, the 12th sellout in Rice-Eccles Stadium history, although hundreds of empty seats were clearly visible.

• Jared Lloyd can be reached at jlloyd@heraldextra.com.