Then the turnovers went in the Patriots direction.
New England scored touchdowns on three of the four that Philadelphia committed, and the Patriots beat the Eagles 42-35 in Brady's preseason debut Friday night.
"We always try to aggressively attack the ball," New England coach Bill Belichick said. "Those can be game-changing plays so when you get a chance to make them, you need to make them."
All six quarterbacks did a good job with their opportunities, a sign that both teams have depth at that position.
Every one of them who played — Brady, rookie Jimmy Garoppolo and Ryan Mallett for the Patriots (1-1) and Nick Foles, Mark Sanchez and Matt Barkley for the Eagles (0-2) each threw at least one touchdown pass.
The Eagles rarely had the ball early.
And when they got it later, they kept giving it away.
"I think the big thing in this game is we just can't turn over the ball and we can't shoot ourselves in the foot," Foles said.
New England had two offensive series before the Eagles had even one since the Patriots' first ended with Williams' 77-yard interception return. Williams hurt his hamstring on the play and didn't return.
Brady threw the ball to Steve Maneri, but the tight end who had signed five days earlier didn't turn around.
"It's just miscommunication," Brady said. "I'm glad it happens in the preseason."
The Patriots tied it on their next possession on a 15-yard touchdown pass to Kenbrell Thompkins, ending Brady's night after completing 8 of 10 passes for 81 yards in two series.
"We always try to aggressively attack the ball... when you get a chance to make [turnovers], you need to make them" - Bill Belichick
Then Philadelphia's turnovers began.
Ifeanyi Momah lost a fumble after catching Foles' pass on their first offensive play. Sanchez threw an interception on his second play of the third quarter and Momah lost another fumble midway through the third quarter after a reception on Barkley's first play.
And on the second play of Barkley's next series, his pass was picked off by Nate Ebner.
Add Alex Henery's missed 47-yard field-goal attempt and a bunch of penalties and coach Chip Kelly has many mistakes to point out after a sloppy performance that followed three days of joint practices with the Patriots.
Reviewing the penalties will keep both coaches busy.
The Patriots committed 11 for 83 yards and the Eagles were flagged for 10 for 86 yards.
At least the officials had warned the teams in meetings during the week that there would be an emphasis on penalizing contact on receivers.
"You're just handing people first downs," Kelly said. "We better figure it out. And, as I said earlier, whichever team ends up being the most disciplined team from penalties standpoint (is) going to be at a big advantage in this league. It's a challenge to everybody."
The Patriots showed a balanced offense — 250 yards rushing, 245 passing.
"We had the momentum all game," said Mallett, competing with Garoppolo for the No. 2 job.
Garoppolo picked right up after Brady left, throwing scoring passes on his first two series, a 15-yarder to James Develin and a 4-yarder to Brandon LaFell for a 21-7 lead. The pass to LaFell was New England's 35th offensive play. Philadelphia had just six at the time.
The Eagles tied it at 21 at halftime with two scoring passes in the last four minutes, a 6-yarder from Foles to Zach Ertz and a 6-yarder from Sanchez to Arrelious Benn.
The score was tied 28-28 before touchdowns by two free agents, a 17-yard catch by Brian Tyms from Mallett and a 10-yard run by Roy Finch that gave the Patriots a 42-28 lead with 5:15 left in the third quarter.
Barkley's 27-yard scoring pass to Henry Josey cut the lead to seven points on the last play of the third quarter. The Eagles drove to the Patriots 1-yard line, but were stopped on fourth down with 4:39 to go.
"We still have some things to get better at," Eagles linebacker DeMeco Ryans said, "but that's what preseason is for."
NOTES: Every quarterback put up solid numbers. Garoppolo was 6 of 12 for 72 yards and two touchdowns and Mallett completed 7 of 11 for 92 yards and a touchdown while playing the entire second half. For the Eagles, Foles was 8 for 10 for 81 yards and one touchdown, Sanchez was 11 for 12 for 117 yards and two touchdowns and Barkley was 9 for 12 for 132 yards and one touchdown. ... The Eagles top two receivers missed the game, Riley Cooper with a foot injury and Jeremy Maclin with a hamstring injury.