Browns' Alex Mack voiding three years left on deal

— -- Cleveland Browns center Alex Mack is voiding the three years remaining on his contract and is set to become a free agent, a source told ESPN's Adam Schefter.

Mack had $24 million remaining on the deal and could once again become the NFL's highest-paid center. A return to Cleveland, the source told Schefter, is still "very probable."

Mack visited with the Browns in February. He met with coach Hue Jackson, director of football operations Sashi Brown and new offensive line coach Hal Hunter to see the direction of the Browns.

Brown said talks were about Mack's role and the new leadership's "vision for winning."

Mack, 30, had to decide on the opt-out by Friday, with unrestricted free agency beginning March 9. It is in his contract that he cannot be tagged. 

He was a first-round pick by Cleveland in 2009, and has been to the Pro Bowl in two of the past three seasons. He is one of the NFL's top interior linemen.

Mack secured a five-year, $42 million contract, which included $18 million guaranteed, from the Browns in 2014 after the club used the transition tag on him. Jacksonville signed Mack to an offer sheet, which the Browns matched.

"My estimation would be if he's going to be in Cleveland, we'll get to a deal before we get to the opt-out," Brown said in February.

With Mack opting out, two of the Browns' best offensive linemen would be unrestricted free agents.

Right tackle Mitchell Schwartz, a second-round pick in 2012, is also set to hit the open market. Schwartz has been consistent and dependable -- playing in 4,427 of the 4,427 offensive snaps since he became a Brown.

ESPN's Pat McManamon and The Associated Press contributed to this report.