Knighton has started all but three games the last three years, missing a trio of games a year ago due to an ankle injury. Alualu has answered the call for 32 consecutive games the past two seasons since the Jaguars made him their No. 1 pick in the 2010 draft.
But things could be different this year.
Both incumbents are being pushed by a pair of relative unknowns. C.J. Mosley has moved ahead of Knighton on the depth chart and started last Friday's preseason game against the New York Giants. D'Anthony Smith, who is pushing Alualu, was also a starter, but Alualu was held out by the coaching staff as a precautionary measure.
Both Knighton and Alualu had offseason surgeries. Alualu's surgery was in January and was done to clean up some issues with his knee that hampered his play a year ago. He had the benefit of extra months to rehab and was nearly 100 percent by the time training camp opened.
Knighton underwent eye surgery in April following a melee at a local nightclub in which he was struck in the eye with a bottle. Last week the surgeon who performed the operation said it was miraculous that Knighton didn't lose his sight in the eye.
With Knighton forced to miss all of the offseason drills, he was behind others when training camp opened. Mosley was quick to take advantage of the opening and has performed well thus far.
Winning a starting spot on the D-line was not a priority coming into camp, he said.
''I just came in here thinking I would give it everything I had,'' said Mosley. ''What's happening at the position, that's up to the coaches to decide. My job is to go out there and play hard every play of every series.''
Mosley appeared in 15 games with the Jaguars a year ago with a career-high three starts. The Jaguars (No. 31 in the AP Pro32) apparently liked what they saw in the former sixth-round pick of the Minnesota Vikings, rewarding him with a three-year, $7.5 million deal. That's given Mosley added incentive to perform well.
''Sure that's an inspiration for me to prove that I'm worthy of the deal,'' he said. ''But like anything I've got to keep working hard. Nothing is etched in stone. My teammate T. Knighton is working very hard. I love him. We push each other every day.''
Mosley has shed some weight, which he feels will benefit his overall game. A year ago he was in the 312-315 range but he's dropped nearly 10 pounds and will play at 305-307 this season.
''Coach (Joe) Cullen says you should drop five pounds every year you're in the league,'' Mosley said. ''I like it. I feel better. Most of my weight is in my stomach or my legs. I feel more flexible and a little more bouncy.''
When Knighton was out with an ankle injury for three games a year ago, Mosley stepped in and performed well. His stock has been on the rise since that time, Cullen said.
''When Terrance went down, C.J. had to start a few games and played great technique,'' Cullen said. ''He played really well on the run game and brought us a little bit on the rush. It was a career year.''
Knighton knows he's in for a fight to reclaim his starting spot. For now, he admits Mosley deserves to be the starter.
''He (C.J.) did the right things in the offseason and the OTAs to be the starter. I've got to earn it back.''
In theory, both could be called starters as both will play about equal snaps. The same holds true for the other battle between Alualu and Smith.
Smith's problem in the past has been his ability to stay healthy. He missed his rookie season in 2010 with an Achilles injury and followed that with a season-ending toe injury last year. Both times he was placed on injured reserve before the season started.
''I'm playing with a sense of eagerness,'' Smith said. ''I've been waiting a long time for this.''
Cullen likes what he's seen in Smith so far.
''D'Anthony was snake-bitten but that's behind him,'' the Jaguars defensive line coach said. ''There's great competition at that position but he has the skills and the qualities. He's really playing well to this point.''
NOTES: The news isn't getting better regarding the Jaguars injury situation. Backup C/G John Estes suffered a knee injury in the Giants game on Friday and he may need surgery. He's out for the rest of the preseason for sure and it could be season-ending. CB Derek Coxhurt hurt a hamstring and will likely miss the next two preseason games. The only good news coming on the injury front was that starting G Will Rackley was progressing faster than expected and may by back by the third preseason game at Baltimore on August 23 ... Less than a week after signing his contract and reporting to training camp, first-round draft pick Justin Blackmon was elevated to the first team offense ... Special teams coordinator John Bonamego had praise for P Brian Anger, who was credited with three 50-yard punts, including a 58-yarder that Bonamego said had a hang time of 5.4 seconds.
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