Garrard was scheduled to start after being listed first on the depth chart, but his agent confirmed Friday he's slated to have knee surgery. His absence is likely to knock him out of the three-way battle for the starting quarterback job he was waging with Tannehill and Matt Moore, who started the last 12 games last season for Miami.
Dolphins starting linebacker Kevin Burnett also missed the game despite taking part in warm-ups. Backup offensive lineman Nate Garner was helped off the field in the fourth quarter after sustaining an ankle injury.
Tannehill, taken eighth overall in the 2012 draft, is the Dolphins' quarterback of the future, but he's hoping to convince his coaches to make him a starter right away.
He made a pretty argument for his case on Friday night.
Before his TD pass, a strike down the middle, Tannehill had a touchdown pass to wide receiver Roberto Wallace late in the second quarter overturned by instant replay. Two plays later, Tannehill missed Clay near the sideline on a fourth-and-goal from the 3-yard line.
He was 8 for 9 on his touchdown drive, the highlight a beautiful touch pass to Wallace over a linebacker that was good for 19 yards on a third-and-11. The only incompletion on the drive was a pass that was batted down at the line of scrimmage.
Tannehill, who finished the game with a 106.6 passer rating, entered with 3:16 left in the second quarter to the applause of a sparse crowd still sitting despite a driving rain. His first pass, on a third-and-6, was thrown behind wide receiver Julius Pruitt and led to a three-and-out.
Matt Moore got the start in Garrard's place and completed 7 of 12 passes for 79 yards with one interception for a rating of 43.4.
Moore, though, was the victim of some bad luck. He produced three first downs on his first drive, only to see Chad Johnson let a pass go through his hands on third-and-3 from the Tampa Bay 33. It was the only pass thrown in Johnson's direction.
The Dolphins' second-round pick of the 2012 draft, tackle Jonathan Martin, also got extended playing time but had an up-and-down performance. Martin started at right tackle and played into the third quarter, long after the other starting offensive linemen had left the game. Martin held up well in pass protection but also was flagged for two false starts.
For Tampa Bay, the game was a good start under new head coach Greg Schiano.
The Bucs looked sharp offensively at the start of the game, scoring touchdowns on their first two possessions.
Starting quarterback Josh Freeman left the game after playing only one series, completing 4 of 5 passes for 41 yards. LeGarrette Blount finished off the drive with a 1-yard touchdown plunge on fourth-and-goal.
Bucs first-round pick Doug Martin scored on a 2-yard run on Tampa Bay's next drive and finished with 21 yards on seven carries.
Tampa Bay's third-quarter field goal was set up by a 74-yard kickoff return by rookie seventh-round pick Michael Smith, a running back from Utah State.
Tom Brady has won his appeal against the NFL, with U.S. District Judge Richard M. Berman criticizing commissioner Roger Goodell for dispensing "his own brand of industrial justice."
Tom Brady wasn't even present for Thursday night's preseason finale between the Patriots and Giants at Gillette Stadium, but he was still the story of the night.
In his weekly radio interview, Patriots president Jonathan Kraft said the team feels vindicated by a federal court decision to overturn Tom Brady's ban and that the team is "ecstatic" for Brady.
Tim Tebow threw two touchdown passes against the New York Jets, his former team, in a strong effort to make the Philadelphia Eagles' 53-man roster.
A week of tumult and controversy continued for the Washington Redskins, who made an off-field stir related to their ticket policy on Thursday before their final preseason game.
Jason Pierre Paul plans to return to the New York Giants next week and the team will examine his hand and make a determination about when he might be available to play, according to a source.