The two scores gave the Dolphins a 24-7 lead and they hung on in the fourth quarter.
The first-teamers, who dominated against Jacksonville the previous week, played into the second half but weren't overwhelming.
Ricky Williams, for example, had no running room and finished with minus-1 yard on nine carries before being taken out in the second quarter.
The Dolphins took the lead in the first quarter after James McKnight forced a fumble on an Atlanta punt return and Morlon Greenwood recovered. The Dolphins then put together a 52-yard drive, culminated by Jay Fiedler's 1-yard touchdown pass to fullback Obafemi Ayanbadejo on fourth-and-goal.
Atlanta cut the lead to 10-7 late in the second quarter when Sam Madison fell asleep and let Peerless Price beat him deep for a 35-yard touchdown.
The Falcons never really threatened after the Dolphins took their 24-7 lead, but they did make it closer after Rosenfels was sacked from the blind side, fumble and Atlanta defensive end Demetrin Veal ran 40 yards with the loose ball to make it 24-14.
Two more Mare field goals made it 30-14 before the Falcons tacked on a late touchdown on a pass from Kurt Kittner to Jimmy Farris.