The Oakland Raiders have asked left tackle Donald Penn to take a pay cut, which may decide his future with the team, Michael Gehlken of the Las Vegas Review-Journal reports.

Penn, 35, is just entering the first year of the two-year, $21 million extension he signed last summer. He held out all of training camp in search of the deal, and the Raiders eventually handed it to him after the start of the season.

Penn is still on the physically unable to perform list after undergoing foot surgery in December.

Gehlken notes that the Raiders are uncomfortable with the structure of the contract for 2018 with Penn coming off a major injury. Half of Penn’s $6 million base salary is fully guaranteed, and he can earn an additional $2.35 million in bonuses and incentives.

The Raiders could potentially look to convert the unguaranteed half of Penn’s base salary into bonuses or incentives.

Penn has been with the Raiders for the last four years. He is a three-time Pro Bowler — including the past two years in a row — and has been remarkably durable for his career. The two games he missed last season were the first in his entire 11-year NFL career.

However, Penn faces competition for his left tackle job this year. The Raiders spent two of their top three picks on offensive tackles, selecting Kolton Miller in the first round and Brandon Parker in the third. Miller would likely be first in line to replace Penn at left tackle should Penn refuse the pay cut and the Raiders choose to move on from the veteran lineman.