Tramaine Brock has agreed to a four-year, $16 million deal with the San Francisco 49ers.

Brock's deal includes $7 million in guaranteed money.

Brock's first start will come on Monday with Tarell Brown injured.

"He's gone from not playing, to being in the nickel, which is a part-time job, to now it's amped up another level that he's in there every play," defensive coordinator Vic Fangio said Friday.