ORLANDO, Fla. (AP) -- Running back Arian Foster had a 2-yard touchdown run in the Miami Dolphins' 17-6 win over the Atlanta Falcons on Thursday night.

Foster, who joined the Dolphins during the offseason and is coming off an Achilles injury, had his most extensive playing time with his new team in the third preseason game that was played at Orlando's Camping World Stadium.

The four-time Pro Bowl running back played in just one series in the first half, but he made the most of the limited opportunities by sparking the Dolphins to their lone touchdown drive of the half with five carries for 10 yards, capped by his 2-yard scoring run early in the second quarter.

More from FoxSports

The Dolphins are taking a cautious approach with Foster, who hasn't played a full season since 2012 with Houston. The former Texans star didn't play in the Dolphins' preseason opener and had just two carries for minus-5 yards last week against Dallas.

With Foster expected to challenge second-year running back Jay Ajayi in the Dolphins backfield this season, coach Adam Case came into Thursday night's game wanting a little more to evaluate Foster on.

Foster didn't get a lot more work, but he did enough in the seven touches he received to make the Dolphins' running back competition interesting. Ajayi carried seven times for 11 yards and caught two passes for 12 yards.

Foster had two receptions for 20 yards, which included a 16-yard catch that moved the Dolphins into scoring position at the Falcons 22.

Dolphins quarterback Ryan Tannehill, coming off an impressive outing against the Cowboys, didn't put his team in many scoring positions, but he did move the ball effectively.

He completed 20 of 29 passes for 155 yards while leading the Dolphins to a score in one of two red zone opportunities.

Last week against the Cowboys, Tannehill led the offense to scores in two of three trips into the red zone.

Falcons quarterback Matt Ryan, meanwhile, took a step back from his showing last week against Cleveland. He completed 12 of 22 passes for 129 yards, no touchdowns and one interception.

In his only trip into the red zone in two full quarters, Ryan threw an interception in the middle of the end zone to Dolphins safety Reshad Jones after moving the offense to the Miami 8 in the second quarter.

The Falcons couldn't get much going and wide receiver Julio Jones left in the second quarter with an ankle injury.

The Dolphins' defense, led by a strong push from defensive tackle Ndamukong Suh and the return of defensive end Cameron Wake, kept the Falcons out of the end zone.

Suh left the game with an ankle injury during the first half.

ROOKIE WATCH

Falcons: Safety Keanu Neal did some good things in the Falcons secondary before an injury forced him to leave the game.

Dolphins: Rookie left guard Laremy Tunsil continued to play well.

POSITION BATTLES

Falcons: Receiver Mohamed Sanu had two catches for 19 yards on three targets during the first three quarters, while Justin Hardy had just one catch for 11 yards in four targets as the two compete for the No. 2 receiver spot.

Dolphins: Center Anthony Steen got the start over injured veteran Mike Pouncey and played well except for a bad snap that resulted in a fumble during the first half.

INJURY UPDATE

Falcons: Safety Keanu Neal went down late in the first quarter with a knee injury. Defensive end Adrian Clayborn suffered a shoulder injury in the first half. Julio Jones left with an ankle and defensive end Dwight Freeney did not make the trip because of a shoulder injury.

Dolphins: Defensive tackle Ndamukong Suh left the game with an ankle injury. Running back Isaiah Pead suffered a hamstring injury and linebacker Jelani Jenkins injured his ankle.