Stewart set a Brut Sun Bowl record with a career-high 253 yards rushing, while Roper, a redshirt freshman, threw four touchdown passes in his first start to help Oregon beat South Florida 56-21 on Monday.
"I knew I was ready to play," Stewart said. "I knew I was ready to run today. I think I played well, but I'll give all the credit to the offensive line for opening up the truck lanes."
The Ducks (9-4) scored 28 straight points in the third quarter to snap a four-game postseason losing streak, their first bowl win since beating Colorado 38-16 in the Fiesta Bowl after the 2001 season.
Oregon made it look easy against the Bulls (9-4), who boasted one of the nation's better defenses. Credit the legwork by Stewart, as smooth a runner as you'll find, and steady play by Roper, who had three weeks to prepare.
"I didn't expect to have that many stats. I expected to do well, but not that well," said Roper, who completed 17 of 30 attempts for 180 yards with no interceptions. His tied a Sun Bowl record with the four TD passes.
The Ducks also won for the first time since losing quarterback Dennis Dixon to a knee injury in November, snapping a three-game losing streak that killed their national title hopes.
"Losing a Heisman Trophy candidate -- the leading Heisman Trophy candidate -- was a big blow," Oregon coach Mike Bellotti said. "It took us a couple of games to recover."
How easy was it this time for the Ducks? They won a matchup of teams that'd been ranked No. 2 in the nation earlier this season handily, despite setting a Sun Bowl record with 138 penalty yards.
But Oregon's offensive and defensive lines set the tone after halftime, and the Ducks never looked back.
"It came down to two things: Jonathan Stewart running the way he's capable of and Justin Roper directing the offense without mistakes and making some plays in the red zone," Bellotti said.
On the next play from scrimmage, Walter Thurmond stepped in front of a pass by South Florida's Matt Grothe and returned it 25 yards for another TD, giving the Ducks a 39-14 lead midway through the third.
"Second half, I can't explain what happened," Bulls coach Jim Leavitt said. "We didn't play good enough defense. That's all there is to it, and when you have those turnovers you have no shot at all."
But these hard-hitting Quackers weren't finished. Grothe had another interception on the ensuing possession, the first of two for Oregon's Jairus Byrd, setting up Roper's 8-yard TD pass to Stewart.
On that drive, Stewart got free on a 16-yard gain, breaking the previous Sun Bowl record of 197 yards rushing set in 1977 by LSU's Charles Alexander in a 24-14 loss to Stanford.
Just like that, Oregon's 18-14 halftime lead had swelled to 46-14, and fans of the Ducks began wondering if Stewart, a junior, will return next fall.
"One more year!" the Oregon fans chanted as Stewart hoisted the Sun Bowl trophy.
"I haven't made any decision," Stewart said later.
For good measure, Ducks kicker Matt Evensen added a 30-yard field goal early in the fourth quarter and defensive end Michael DiVincenzo returned an interception for a touchdown with 3:23 remaining.
Roper opened the season fifth on the depth chart and ran the scout team until a series of quarterback injuries -- none more devastating than the loss of Dixon -- reshaped the Oregon roster.
Bellotti gave Roper the start over Cody Kempt, another redshirt freshman.
"With Justin Roper's development over the course of our bowl practices, I felt he was sort of a secret weapon," Bellotti said.
Stewart was just as impressive. He broke a 71-yard TD run late in the second quarter, greeted by an enormous hole off left tackle, and raced untouched to the end zone to give the Ducks an 18-11 lead.
Stewart kept the momentum going after the break. His 41-yard run on Oregon's first drive of the second half set up Roper's second TD pass for a 25-14 lead, and he logged the ninth-best rushing effort in a bowl game.
"He was a big running back," said South Florida end George Selvie, the Big East's defensive player of the year. "He ran hard. He never stopped pumping his legs."
There was no sign of the turf toe injury that slowed Stewart earlier this season, when Oregon dropped from the national title chase.
South Florida, which reached No. 2 in the country in just its 11th season playing football, missed a chance to win 10 games for the first time.
"If people said it wasn't a positive season, I'd be a little disappointed," Leavitt said. "We've never won nine games in 11 years. I think it was a heck of a season. We don't have any excuses, though."
The 49,867 fans were treated to lots of penalty flags. The teams combined to break the Sun Bowl record for total penalty yardage -- 202 penalty yards -- and it wasn't even halftime when the old mark fell.
"I told our team we needed to play with greater poise, that the [halftime] score was not indicative of the type of game we were capable of," Bellotti said. "We were helping them with penalties. We were not playing with great intelligence."