The 49ers reportedly reached contract terms early Wednesday morning with NFL All-Decade center Alex Mack.
Mack, 35, a 12-year NFL veteran, is expected to sign with the 49ers, the NFL Media's Ian Rapoport reported.
The official start of NFL free agency is scheduled for Wednesday, 1 p.m., at which point players are allowed to sign with other teams. The NFL’s open negotiating period began Monday at 9 a.m.
Mack and the 49ers always figured to be a good fit, as the 49ers were looking to upgrade at center.
Mack previously played under coach Kyle Shanahan with the Cleveland Browns and Atlanta Falcons. Shanahan was the offensive coordinator with those teams.
Mack told NBC Sports Bay Area in early February he would welcome an opportunity to reconnect with Shanahan and play in California.
“Kyle is an incredible coach,” Mack said. “He’s an incredible coach, great person, strong motivator and runs an offense that is something that I’d know really well and that I performed very well in.
“Yeah, that said, they (the 49ers) are a very enticing thing."
Mack has been named to the Pro Bowl team six times in his career. The Southern California native attended Cal, where he was a two-time winner of the Morris Trophy, awarded to the best offensive lineman in the Pac-12 Conference. He was the No. 21 overall pick of the Browns in 2009.
Mack described the requirements from the center position in Shanahan’s offense.
“You have to snap the ball and you have a guy who’s bigger and heavier than you who can just jet upfield,” he said. “So you have to create ways and use different schemes to try to get that block to happen and help it out.
“What Kyle has done very well in the past is he's always been able to link different plays and different schemes so they all look pretty much the same. But it takes advantage of the different things a defense will do. It’s a very smart offense, which is fun.”