OXNARD, Calif. (AP) -- Dallas defensive end DeMarcus Lawrence faced his teammates in the spring, apologizing for a violation of the NFL substance-abuse policy that will sideline him for the first four games this season.
The next step was addressing the suspension publicly, which the third-year player did on the second day of training camp Sunday with the Cowboys.
"My disappointment is it's on me," Lawrence said. "I messed up. I learn from my mistakes and I just have to move on and get everything right."
Lawrence's ban was one of three in the offseason for the Dallas defense under the substance-abuse policy. Fellow pass rusher Randy Gregory will miss at least four games and faces a longer suspension over another failed drug test. Linebacker Rolando McClain already has a 10-game suspension.
The 24-year-old Lawrence is the only one of the three to report for camp.
Gregory is in rehab, raising doubts about whether he will play at all a year after sliding to the Cowboys late in the second round of the draft when he failed a marijuana test at the NFL combine. McClain didn't report after staying away from the team most of the offseason.
Both are on the reserved-did not report list, subjecting each to $40,000 daily fines and leaving Lawrence to answer for suspensions that snared three starters.
"I can't speak for nobody else. I just know my situation," said Lawrence, who led the Cowboys with eight sacks last season. "I just made a mistake. Everybody makes mistakes. But it's what you do from it."
Lawrence is also coming off back surgery in the offseason and is unlikely to go full speed in camp with the suspension looming as well. He's eligible for preseason games, so the coaching and medical staffs will have to decide how far to go to get him ready for Oct. 9 against Cincinnati.
"You have to get them ready," coach Jason Garrett said. "He's going to get plenty of work. I do think we can achieve both things, where he still gets his work and lays a foundation for the season, and you still get the other guys an opportunity."
Lawrence missed the first half of his rookie season when he broke his foot early in training camp two years ago. He started to show up late that season, getting one sack in the regular season and another in the playoffs. He started slowly last season before getting seven sacks in the final eight games.
Now he'll have another slow start because he won't be out there until Week 5.
"I'm going to deal with it by trying to help my young guys and making sure they're ready," Lawrence said. "I'm just going to work as hard as I can off the field, you know? Just by doing film studies and giving them little keys or whatever they need. I'm here for the team."
Garrett said Lawrence delivered that message in the spring.
"He's a good person," Garrett said. "He's a good teammate. He works hard. He wants to be the best he can be and he wants his team to be the best it can be. I think he's acted accordingly since then."
NOTES: QB Tony Romo skipped the second camp workout Sunday in order to be available for the first two padded practices Monday and Tuesday. The routine will be similar to 2014, when he was coming off back surgery and had roughly a day off for every two workouts. ... Garrett said several other veterans will get periodic days off, including Dez Bryant. The 2014 All-Pro receiver is coming off two surgeries after breaking his right foot in the opener last year.
