SANTA CLARA, Calif. (AP) In a trying offseason for the San Francisco 49ers that featured a number of key losses, one star player's comeback is providing a glimmer of hope.

Inside linebacker NaVorro Bowman is nearing the end of the road in his recovery from surgery on his left knee.

After donning pads for the first time in nearly 19 months to start training camp, he is questionable to play in Saturday's preseason opener against the Houston Texans, head coach Jim Tomsula said Thursday.

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Having lost the likes of Patrick Willis, Justin Smith and Aldon Smith, Bowman understands how his return might help his team without the trio that combined for 13 Pro Bowls.

''I was a young guy,'' Bowman said. ''Just to see older guys go down at some point in the season, when they came back, the morale of the team changed. You could just feel it. If the guys look at (my return) that way, then I'm grateful.''

Bowman tore his ACL and MCL in the NFC championship game against the Seattle Seahawks in January 2014, and missed all of last season while recovering. That long process, Bowman said, was boring and lonely.

''It's a gut check, because you ask yourself, `Do you really want to do it?' sometimes,'' Bowman said. ''Those are the things that go through rehabilitation, is just fighting through those tough days when your knee is sore.''

Bowman was activated to the 53-man roster during his rehabilitation on Dec. 9, but never practiced, and was placed on season-ending injured reserve four days later.

Although Bowman isn't quite back to peak form, his presence in the middle of San Francisco's defense on the practice field is felt. The coaching and medical staffs are working closely with Bowman to ensure he doesn't put undue stress on his knee, which is why many of his practice reps are not full speed.

Bowman has been forced to wear a bulky knee brace during team drills.

When Bowman has gone full tilt in training camp, he's shown flashes of the player that garnered Defensive Player of the Year consideration in 2013, when he led the 49ers with 143 tackles, five sacks and four forced fumbles.

During the first practice of training camp, Bowman blitzed Colin Kaepernick using a swift spin move on right guard Marcus Martin, leaving Martin flat footed for a sack. ''He's looking 100 percent out there,'' Martin said later. ''He's rolling right now.''

In a practice this week, Bowman sacked Kaepernick and intercepted him on consecutive plays.

''He's so eager to be out there,'' second-year cornerback Dontae Johnson said. ''He's probably one of the happiest players to be able to put back on pads and the helmet, and to be back out there with us. It's exciting.''

Bowman's insertion into the starting lineup in 2011 helped catalyze the 49ers' run to three straight conference title games under former head coach Jim Harbaugh. But Bowman had the help of Willis and the Smiths. Bowman and outside linebacker Ahmad Brooks are the only starters left from the defense that reached the Super Bowl three seasons ago.

Now, Bowman returns as the unquestioned leader of the defense that could field new starters at seven positions.

''That's what I live for, to lead,'' he said. ''I always strive in setting examples. Studying just like a coach. Just trying to know as much as a coach knows, just trying to be his voice out on the field. That's just who I am.''

Even if Bowman does not play Saturday, Tomsula said he will get snaps at some point during the preseason.

Tomsula said running back Reggie Bush, receiver Bruce Ellington, linebacker Philip Wheeler, receiver Dres Anderson, linebacker Nick Bellore, running back Kendall Hunter, linebacker Aaron Lynch, center Daniel Kilgore, receiver DeAndre Smelter, defensive back Jimmie Ward and linebacker Michael Wilhoite will be held out of Saturday's game.

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