SPARTANBURG, S.C. (AP) -- Go ahead, you try telling Carolina's Byron Bell and Thomas Keiser the NFL preseason doesn't matter.
They know better.
Bell and Keiser arrived at Panthers training camp last summer as undrafted rookies and heavy underdogs to make the 53-man roster. Both overcame those odds after strong performances in the preseason and are now expected to be key contributors for the Panthers.
Bell made the opening-day roster last year, started 12 games at right tackle and is now viewed as the team's long-term answer at that position. Keiser's relentless motor prompted the Panthers (No. 20 in AP Pro 32) to sign him to the practice squad, where he eventually fought his way onto the roster and registered four sacks in eight games as a reserve defensive end.
Panthers coach Ron Rivera said both should serve as motivation for other undrafted rookies and first-year players who think they're facing an uphill battle to make the roster entering the preseason, which kicks off Saturday night against the Houston Texans (No. 6).
Rivera reminded players this week that because of injuries the Panthers used 17 extra guys last season - many of those went to training camp with the team.
''Right now it's an opportunity to show us that, hey, if you have a redeemable quality where even if we let you go at the end of training camp we can still bring you back,'' Rivera said. ''So they're not only fighting for a roster spot or a practice squad spot now, they're fighting for the future.''
Rivera said the coaches place huge emphasis on games when it comes to choosing the team's final roster in late August.
''I think the preseason is definitely huge for guys showing their value to the team,'' Keiser said. ''That was how I became relevant in the coaches' eyes last year, playing the six-technique and knocking the tight ends off the ball. That was the first little thing where they started thinking, hey, maybe there's something with this guy.''
Bell actually missed the first two preseason games last year with an injury, but came on strong after getting extensive playing time in the final two.
''I played pretty well in the last preseason game and I think that's what saved me,'' Bell said.
Not that there wasn't some anxiety for Bell along the way.
Looking back he acknowledged being a little nervous heading in for his first NFL action after playing his college football at New Mexico.
''I was nerve wrecking and, quite frankly, I was a little star-struck at first,'' Bell said. ''But at the end of the day it's just football. That's all it is. That's the way you have to think of it.''
Keiser said he learned a new approach to the game last preseason.
On the day before Carolina's preseason opener, the Panthers practiced in full pads - something teams don't do during the regular season.
''It was weird for me and I was a little confused thinking, 'Aren't we playing a game tomorrow?''' Keiser said. ''So I showed up at the stadium and treated it like a practice. I just went out and tried to fly around and make the most of it. I stayed really loose and I ended up playing really well and figured I was on to something.''
He took that same approach into the regular season when he was activated.
''I look back on my college career and realized I was probably wound too tight for most of those games,'' said Keiser, who played at Stanford. ''That preseason game just changed my whole mentality about how I prepared for a game. You want to have that focus but you don't want to be too tight. I just said I'm going to play as fast as I can and know my assignments and stuff will fall into place.''
The NFL has discussed the possibility of shortening the preseason to two games, although that idea has been shelved for future debate.
Right now they'll stick with four.
Bell said if it ever is reduced to two games it might make it tough on undrafted rookies to prove themselves to coaches.
''They show what you can do, especially with the coaches who are making the decision on whether they keep you,'' Bell said. ''It's a chance to show the coaches what you're about.''