SAN FRANCISCO Aldon Smith, who flirted with an NFL rookie record for sacks last season, left Friday's game in the first quarter with a hip injury and did not return.
Smith appeared to suffer the injury on the first play of the Vikings' second drive, a three-yard run by Toby Gerhart to Smith's side of the field. Smith was cut down by a blocker and got to his feet slowly.
He remained in the game for another play, but then jogged gingerly to the sideline. He had a pronounced limp while walking into the training room and later left the locker room with the help of two canes.
The 49ers characterized the injury as a hip bruise.
"Preliminarily, looks like we'll be all right," coach Jim Harbaugh said. "Looks like we dodged a bullet there."
Undrafted rookie Kourtnei Brown filled in at right outside linebacker on the first play that Smith missed. Veteran Parys Haralson, however, soon replaced him on the first-team defense.
Finding depth at outside linebacker was a goal for the 49ers in the offseason. They made it through the 2011 season with only three players at the position but admitted it was a gamble.
They drafted two outside linebackers in April, but both players, fifth-rounder Darius Fleming and seventh-rounder Cam Johnson, did not dress for the game.
Smith finished with 14 sacks last season, coming within a half sack of Jevon Kearse's rookie record set in 1999.
Smith had a quarterback hurry on the drive before he was injured.
Precious commodity The 49ers gave veteran defensive end Justin Smith the day off Friday. Smith, an 11-year veteran, was one of six 49ers not in uniform for the game.
The others were recovering from recent injuries. They included Johnson and Fleming, defensive lineman Will Tukuafu, tight end Nate Byham and wide receiver Joe Hastings.
Running back Frank Gore was in uniform but did not play. Kendall Hunter started the game at tailback.
Backup Ricky Jean Francois started at right defensive end for Justin Smith, who is one of the 49ers' most indispensable players this season. Smith finished second on the team with 7½ sacks last year but was credited for helping teammate Aldon Smith, who also lines up on the right side, finish with 14 sacks.
Et cetera Kyle Williams returned his first punt at Candlestick Park since his infamous outing in the NFC Championship Game on Jan. 22. Williams not only fielded it cleanly, he returned it 22 yards, hurdling Vikings safety Andrew Sandejo along the way.
First-round pick A.J. Jenkins made a nice catch along the sideline for a 15-yard gain. Two plays later, however, he dropped a short pass from Colin Kaepernick and had another drop on a throw from Scott Tolzien.
Last year's preseason surprise, Demarcus Dobbs, officially has changed his uniform number to 40 and is listed as a tight end. Dobbs played defensive end exclusively in the first half.