PITTSBURGH -- Aaron Rodgers and Ben Roethlisberger look ready for the regular season.

The immediate future for Jordy Nelson seems far more uncertain.

The Green Bay Pro Bowl wide receiver limped off with a potentially serious left knee injury in the first quarter of the Packers' 24-19 preseason loss to the Steelers on Sunday. Nelson landed awkwardly while trying to cut after making an 8-yard reception on Green Bay's opening drive and did not return.

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

Roethlisberger played into the second quarter, connecting on 11 of 14 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.

Rodgers threw a surprising 19 passes in the preseason opener against New England last week. He didn't come close to that against the Steelers, though the most significant throw Rodgers made came on a relatively innocuous hitch to Nelson on sixth play from scrimmage.

The Packers were driving when Rodgers found Nelson on the right side for a short gain. Nelson appeared to have plenty of room to run when defensive back Antwon Blake slipped on the turf. When Nelson tried to cut, however, his left leg slid underneath him, sending Nelson tumbling to the ground.

Nelson managed to gingerly make it to the sideline under his own power before being taken to the locker room for further examination, a potentially devastating blow for the Packers and for the wide receiver who set career highs in receptions (98) and yards receiving (1,519) in 2014.

Lacy gave the Packers the lead four plays after Nelson's exit with a remarkably easy 7-yard touchdown sprint through a massive hole on the left side of the line. A 2-point conversion by James Starks -- through an equally massive hole on the right side -- put Green Bay up 8-0.

Pittsburgh's defense regrouped on Green Bay's next possession, with 37-year-old Harrison beating backup left tackle Don Barclay -- filling in for injured starter David Bakhtiari -- and slamming into Rodgers in the end zone for a safety.

The Steelers' anxious injury moment came minutes later when Green Bay cornerback Ha Ha Clinton-Dix rolled into Pouncey while making a tackle. Pouncey limped to the sideline before being taken to the locker room on a cart. Pouncey missed all but eight snaps of the 2013 season after tearing multiple ligaments in his right knee in the season opener against Tennessee.

Roethlisberger found a rhythm on his final drive, leading the Steelers 51 yards in seven plays, the last one a little 5-yard flip to a wide open Markus Wheaton that put the Steelers up 9-8 before the backups took over.

Green Bay second-string quarterback Scott Tolzien completed 11 of 19 passes for 102 yards and a 21-yard score to Richard Rodgers.

Pittsburgh's Landry Jones, trying to convince the Steelers to keep him around as a third option, tossed a pair of fourth-quarter touchdowns to complete a rally from a 10-point deficit.