Updated

NASHVILLE, Tenn. (AP) Marcus Mariota turned in a clean performance in his home debut, Tennessee cornerback Perrish Cox returned an interception 24 yards for a touchdown and the Titans beat St. Louis 27-14 on Sunday night to spoil Rams coach Jeff Fisher's return to town.

A week after Mariota was sacked, threw an interception and lost a fumble that was returned for a touchdown, the No. 2 pick overall out of Oregon was 5 of 8 for 58 yards with no turnovers.

Titans teammate Dexter McCluster dropped Mariota's pass in the end zone, while Rams safety Mark Barron couldn't hold a would-be interception off the rookie.

Fisher, the winningest coach in Tennessee history after more than 15 seasons, was honored with a video tribute during the first timeout in the first quarter, and he acknowledged a standing ovation with a wave.

Tennessee's defense looked much improved against an offense that ranked 28th in the NFL last year. With Cox's interception, the Titans (1-1) finally stopped an opponent on the opening drive for the first time in six preseason games.

Nick Foles had a rough outing in three series for the Rams (0-2).

STEELERS 24, PACKERS 19

PITTSBURGH (AP) - Green Bay receiver Jordy Nelson limped off with a potentially serious left knee injury in the first quarter of the Packers' loss to Pittsburgh.

Nelson landed awkwardly while trying to cut after making an 8-yard reception on Green Bay's opening drive and did not return.

While Packers coach Mike McCarthy stressed the defending NFC North champions ''will look for good news'' when Nelson is re-evaluated Monday, quarterback Aaron Rodgers expressed equal parts frustration and mystification. ''It's difficult to lose a guy like that in a meaningless game,'' Rodgers said.

Rodgers completed 4 of 5 passes for 57 yards during two series of work for Green Bay (1-1), with one drive ending with a touchdown run by Eddie Lacy and the other with Rodgers getting sacked by James Harrison for a safety.

Ben Roethlisberger played into the second quarter for the Steelers (1-2), connecting on 11 of 14 passes for 100 yards a score. Pittsburgh Pro Bowl center Maurkice Pouncey left with a left ankle injury in the first quarter and did not return.

49ERS 23, COWBOYS 6

SANTA CLARA, Calif. (AP) - Long black hair swinging from his helmet, 303-pound defensive lineman Mike Purcell intercepted Dustin Vaughan's pass and returned it 37 yards for a touchdown to help San Francisco beat Dallas.

Purcell, a practice-squad player in 2013 and for all but the final two games last season, provided the highlight again after his six-tackle day last week in an opening loss at Houston.

Dallas quarterback Tony Romo's day was done after one three-and-out series then the Cowboys turned to Brandon Weeden, who left with a possible head injury.

The Cowboys (1-1) were expected to be cautious with Romo and Co. at Levi's Stadium, where the troublesome grass held up after causing concern for coach Jason Garrett and owner Jerry Jones.

Craig Dahl also added an interception for San Francisco against third-stringer Vaughan. Quinton Patton blocked a fourth-quarter punt by Tom Hornsey and scooped it up in the end zone for a 49ers touchdown.

Dallas avoided a shutout when fourth-string QB Jameill Showers threw an 8-yard touchdown pass to Nick Harwell in the waning moments.

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