Friday marks the first day the Bears can pick up the 2018 option in left guard Josh Sitton’s contract.

The contract Sitton signed with the Bears in 2016 was for two years and included a team option for 2018 that is worth $8 million.

The Bears must decide on Sitton’s option between Friday and March 9 — five days before the start of the new league year. If they decline the option, Sitton will become an unrestricted free agent. The option calls for a base salary of $7.4 million with $500,000 available in roster bonuses ($31,250 per game) and a $100,000 workout bonus.

Sitton, who turns 32 in June, was selected as a Pro Bowl alternate after the 2016 season and has earned $13 million through the first two years of the deal. A four-time Pro Bowl selection, Sitton missed three games last season, including the final two with an ankle injury. If the Bears release him, they will carry a salary-cap hit of only $666,667 in 2018.

Before the Week 17 finale at Minnesota, Sitton indicated he intended to continue playing.

“I’ve taken things day by day for the past couple years,” he said. “I feel really good. … I definitely see myself playing football for the next couple years. Definitely see myself playing. I don’t feel like this is my last season.”

bmbiggs@chicagotribune.com

Twitter @BradBiggs

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