With Tom Brady watching the entire game from the sidelines, the third-round draft choice from Arkansas led four second-half touchdown drives as the Patriots beat the Jacksonville Jaguars 47-12 in an exhibition opener on Thursday night.
But by the time he entered the game at the start of the second half, the Jaguars were playing third- and fourth-string defenders in many spots.
"I felt like I relaxed a little after the first play," Mallett said. "It felt good just to get out there and play with the guys."
Jaguars rookie quarterback Blaine Gabbert was more highly regarded -- he was taken with the 10th pick -- but had a rougher day, although he played the first half when the Patriots used some of their starters on defense.
"I was just excited to be playing football," Gabbert said. "It's preseason and a lot of it you take with a grain of salt."
Gabbert completed 9 of 16 passes for 85 yards and the Jaguars managed just three field goals on his six series. Mallett was 12-for-19 for 164 yards and threw a 16-yard touchdown pass to another third-rounder, Stevan Ridley, who also ran for two 1-yard scores.
"Ryan did a great job," Gabbert said. "He's in the same situation I am. I thought he executed his offense real well."
And, like Mallett, Gabbert likely will spend much of the season on the bench, barring an injury or poor play by starter David Garrard. He missed the game with a back problem but could return to practice on Saturday.
"If something happens to me, like my back, we may need him to be out there," Garrard said, but "I'm feeling better every day."
Mallett helped turn a 19-9 halftime lead into a 35-point rout. The 47 points were the most scored by the Patriots in an exhibition game, passing the mark set on Sept. 4, 1977, in a 45-7 win over the Washington Redskins.
Two other rookies, both running backs, had productive games for the Patriots. Ridley from LSU ran 16 times for 64 yards and caught seven passes for 47 yards. Richard Medlin, a rookie free agent from Fayetteville, had two 2-yard touchdown runs.
""We really looked at a lot of young players, got them in there and let them play. That was the goal tonight," coach Bill Belichick said.
Many top players played sparingly -- or not at all.
Among the Patriots sitting out the game who were part of last year's 14-2 team that lost its only playoff game were 2010 NFL MVP Brady, receivers Wes Welker and Deion Branch and defensive lineman Vince Wilfork. Two newcomers, wide receiver Chad Ochocinco and defensive tackle Albert Haynesworth, also were held out.
The Patriots started a quarterback who wasn't drafted, second-stringer Brian Hoyer. But he spent the past two years with the team and his experience paid off. He completed 15 of 21 passes for 171 yards and an 11-yard touchdown pass to Taylor Price in the first half.
Gabbert was replaced by Todd Bouman on Jacksonville's first possession of the second half.
"I thought (Gabbert) was composed and did a good job making decisions," Jaguars coach Jack Del Rio said. "He looked like he belonged. It was a good beginning."
On Mallett's first series, he completed 6 of 8 passes for 79 yards, setting up Ridley's 1-yard scoring run.
The coaches, Ridley said, "want me to be a downhill runner and that's what I'm going to continue to do."
On the next series, Mallet connected with Ridley for the touchdown pass to cap a 67-yard drive.
On the Patriots' next possession, Mallett threw for 44 of the 80 yards and Medlin got his first touchdown. They didn't have to work as hard for their next score after Buddy Farnham intercepted Bouman's pass. That drive went just 31 yards with Medlin carrying for the last 2.
Before the game, Patriots owner Robert Kraft stood on the sidelines as players ran there after coming out of the locker room. Wilfork hugged Kraft, whose wife Myra died of cancer at the age of 68 on July 20.
The Patriots wore a patch with the initials MHK for Myra Hiatt Kraft on their uniforms.
Gabbert led a decent opening drive, moving the team 57 yards in 12 plays. But after a 4-yard completion to Zach Miller for a first down, he was sacked and threw an incompletion and the Jaguars settled for Josh Scobee's 41-yard field goal.
Jacksonville failed to get a first down on the next three series, settling for just a 40-yard field goal from Sam Swank.
In two seasons at Missouri, Gabbert threw 40 touchdowns and 18 interceptions and had an 18-8 record. The Jaguars traded with Washington to move up six spots and draft him.
Mallett also was one of the nation's best quarterbacks, but character issues may have caused him to slide into the third round.
Richard Murphy led Jacksonville's rushers with 43 yards in 7 carries. ... Second-year Jacksonville running back Deji Karim returned a kickoff 84 yards in the second quarter, but the Jaguars managed just a 29-yard field goal from Scobee that cut the Patriots' lead to 13-9 early in the second quarter. ... Three of the Patriots' nine draft picks this year didn't play -- CB Ras-I Dowling, RB Shane Vereen and OL Marcus Cannon.
Indianapolis Colts quarterback Andrew Luck will not play Sunday against the Jacksonville Jaguars because of a right shoulder injury.
Dolphins coach Joe Philbin isn't worried about his job security after meeting with owner Stephen Ross following the team's third straight loss on Sunday.
More money was bet on the Jets-Dolphins game at Ladbrokes than any previous NFL game played at Wembley Stadium in London, according to a spokesman for the U.K. sportsbook.
Houston Texans running back Arian Foster played for the first time in 2015 against the Atlanta Falcons on Sunday, marking his first game action since tearing his groin Aug. 3.
Bears quarterback Jay Cutler, who has been hampered by a hamstring injury, was active and started Sunday's game against the Oakland Raiders.
Philadelphia Eagles running back DeMarco Murray, who has been hampered by a hamstring injury, was active against the Washington Redskins on Sunday.