The San Francisco 49ers and cornerback Tramaine Brock agreed to a four-year contract extension Friday worth $16 million with $7 million guaranteed and a $4 million signing bonus, a person informed of the deal told NFL Media Insider Ian Rapoport.
Brock's extension with the 49ers comes as he readies for his first career start Monday night versus the Washington Redskins. Brock will be replacing Tarell Brown, who injured his ribs in the Niners' 23-20 loss to the New Orleans Saints in Week 11.
Brock's rise from battling for a roster spot in training camp to starting corner for one of the best defenses in the NFL has been impressive. After surpassing Nnamdi Asomugha on the Niners' depth chart, Brock intercepted a Matt Schaub pass for a pick six to cement his place as the team's nickel cornerback.
Brock, an undrafted free agent out of Belhaven College, has a team-high four interceptions on the season for the 49ers.
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