FOXBOROUGH, Mass. – Ryan Mallett played solidly in his first chance at quarterback for the New England Patriots. He may not get another once the regular season starts.

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 Thursday night.

By the time Mallett 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 three field goals on his six series. Mallett was 12 of 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.

“(Mallett) 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.

Garrard missed the game with a back problem but could return to practice Saturday.

“If something happens to me, like my back, we may need him 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, passing the record set Sept. 4, 1977 in a 45-7 victory against Washington.

Two other rookies, both running backs, had productive games for the Patriots. Ridley ran 16 times for 64 yards and caught seven passes for 47 yards. Richard Medlin had two 2-yard touchdown runs.

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 were Brady, receivers Wes Welker and Deion Branch and defensive lineman Vince Wilfork. Two newcomers, receiver Chad Ochocinco and defensive tackle Albert Haynesworth, also were held out.

Besides Garrard, Jacksonville starters who didn’t play were running back Maurice Jones-Drew, defensive end Aaron Kampman, tackle Eben Britton and cornerback Derek Cox.

The Patriots started quarterback Brian Hoyer, who 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.”