Oakland Raiders left tackle Donald Penn did not report for the start of the team's training camp on Friday due to frustration over his contract, multiple outlets reported.
The 2016 Pro Bowl selection is entering the final season of a two-year contract that has a base salary of $5.8 million, with bonuses and incentives pushing that total to $7.15 million. By comparison, at least 14 offensive tackles in the NFL make $10 million per season.
Penn has yet to miss a regular-season game since entering the league as an undrafted free agent with the Tampa Bay Buccaneers in 2007. The 34-year-old sat out the Raiders' wild-card playoff loss to the Houston Texans last season with a left knee injury.
Should Penn elect to have a lengthy holdout, the Raiders have Marshall Newhouse, David Sharpe and 2017 seventh-round pick Jylan Ware among their options at tackle.