The New England Patriots opened the 2014 season with an ugly 33-20 loss to the Dolphins in Miami, losing their first debut in 11 years.
The Patriots failed to score a point in the second half after leading the Dolphins 20-10 at halftime.
Tom Brady fumbled twice in the debut, with the ball being recovered by Miami both times.
Sunday marked the Patriots' first game after the trade of longtime guard Logan Mankins. The new-look offensive line allowed Brady to be sacked four times.
"We've got to improve in every phase of the game - playing, coaching, offense, defense, special teams - you name it, it just wasn't what we needed to do today," said head coach Bill Belichick. "We didn't do anything well enough in the second half, period."
Ryan Tannehill completed 18 passes in 32 attempts, throwing for 178 yards and two touchdowns and a pick. The Dolphins' offense diversified, with Knowshon Moreno running the ball for 134 yards. Fellow running back Lamar Miller added 59 yards of his own, while Shane Vereen led New England with just 36 rushing yards.
Brady threw for 249 yards, completing 29 of 50 passes. Julian Edelman was a bright spot with 95 receiving yards, making six catches on eight targets.
Brady's sole touchdown pass came courtesy of tight end Rob Gronkowski in his first game back after tearing his ACL in December.
"You win as a team, lose as a team," said Gronkowski. "Just gotta keep on improving, every week."
In his first regular season game with the Pats, star cornerback Darrelle Revis recovered a fumble by Miller.
New England's record is 0-1 for the first time since 2003, when they lost their season opener in Buffalo against the Bills. They went on to win the Super Bowl that year.