Overbay's 7-yard grab capped a 71-yard, 10-play drive and put the Bucs on top to stay.
The Bucs' other TD came on a second-quarter run from Earnest Graham.
The Dolphins were led by Chad Henne, who finished 10-of-13 for 175 yards and a TD toss to Brandon Marshall (two catches, 90 yards).
Matt Moore later took over at quarterback and went 8-of-16 for 90 yards.
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