BALTIMORE (AP) — Tennessee Titans rookie Zach Mettenberger understands perfectly what it takes to be a successful quarterback in the NFL.

Two starts into his professional career, he has yet to fully adhere to the blueprint.

"I think in the last eight quarters we've played, we played four quarters really well," Mettenberger said after the Titans lost 21-7 to the Baltimore Ravens on Sunday. "That doesn't get you wins in this league."

Mettenberger struggled against a Ravens defense that came at him in waves, completing 16 of 27 passes for 179 yards with a touchdown and an interception. He was sacked five times and the Titans twice turned over the ball, once at the Baltimore goal line.

"They got a lot of dudes, they got a lot of studs in that front seven — and they know it," Mettenberger said. "Early in the first half we did a lot of good things to kind of counteract their guys. We just got to continue to ... play like that for 60 minutes."

But the former LSU star was hardly the only reason for another Tennessee loss. The Titans were only 4 for 12 on third down, had seven three-and-outs in their 11 drives and could muster only 68 yards in offense after the first quarter.

"He did some good things today, made some good throws," coach Ken Whisenhunt said of Mettenberger. "I think he did a nice job of operating today in this environment, which is not easy. But obviously, we have to be more productive."

The Titans (2-7) have lost seven of eight. It was 7-all at halftime, but Tennessee had three three-and-outs in the third quarter while the Ravens took control.

Tennessee didn't get its initial first down of the second half until 4:37 was left in the game. Soon after that, newcomer Danny Gorrer intercepted a pass to clinch the victory.

It was a bounce-back performance by a defense that was embarrassed seven days earlier in a 43-23 loss in Pittsburgh. In that game, Ben Roethlisberger threw for 340 yards and six touchdowns.

The Titans lost tight end Delanie Walker in the second quarter with a concussion. Walker, who came in tied for the team lead with 35 catches, got his hands on a pass and was turning upfield when struck high and hard by Terrence Brooks.

The Ravens believe that hit made a lasting impression.

"I think the key play was when (Walker) was turned up," Baltimore linebacker Elvis Dumervil said. "You don't want to hurt a guy, but it was an aggressive, clean hit. It really made guys kind of think about running back there."

Joe Flacco completed 16 of 27 passes for 169 yards and a touchdown for the Ravens, and Justin Forsett ran for 112 yards and two TDs.

Baltimore went ahead for the first time with 5:36 left in the third quarter when Forsett scored on an 11-yard run to make it 14-7. Flacco went 5 for 5 on the 11-play, 72-yard drive.

After the Titans failed to respond, Flacco hit Torrey Smith for a 32-yard touchdown with 13:09 left.

The Ravens made only five first downs and were held to 86 yards in the first half.

Tennessee took the opening kickoff and held the ball for more than eight minutes before Shonn Greene lost a fumble on third-and-goal at the Baltimore 1.

After the Ravens went three and out, Mettenberger capped a nine-play drive with a 3-yard pass to Leon Washington. It was only the second time this season the Titans scored a touchdown in the first quarter.

That, unfortunately, was the highlight of the day for Mettenberger and the Tennessee offense.

"Zach did a good job today," Titans wide receiver Nate Washington said. "He's a young guy. He has room to grow. So, he definitely has some opportunity to get better."

At that point, Tennessee had a 142-8 advantage in total yardage.

Baltimore pulled even with a touchdown on its third possession. On a fourth-and-1 from the Tennessee 9. Forsett took a pitchout and sprinted around Kamerion Wimbley into the end zone.

Forsett earned the starting job after Ray Rice received an indefinite suspension from the NFL for domestic abuse. Now in his eighth season, Forsett has already reached career highs in yards (721), carries (133) and touchdowns (5).

"It's been a dream come true, just to get the opportunity to come out here and play and show what I can do," he said.

NOTES: Titans RB Dexter McCluster left in the first quarter with a knee injury. ... Baltimore's Terrell Suggs had 1 1/2 sacks and stands at 99 1/2 for his career.