The Patriots elevated undrafted rookie safety Sergio Brown to the active roster in a pinch, and he rewarded them Sunday by making one of the most important defensive plays of the game.

Brown, who had been on New England's practice squad until Saturday's promotion, had four total tackles (three solo) in the Patriots' 23-20 victory in San Diego. His last stop, though, directly helped preserve the win.

On San Diego's final offensive play, Chargers tight end Antonio Gates caught a third-and-10 pass on the right side of the field, and Brown — the only player in position to make a play — hauled down Gates two yards before the first-down marker. Kicker Kris Brown missed a field goal on the next play to essentially end the game.

Patriots head coach Bill Belichick said Monday that Brown was activated due to safety Jarrad Page's injury, and it sounded like Brown was going to be used on special teams and as an emergency, fourth-string safety. When Patrick Chung injured his knee in the first half — an injury that could sideline Chung for one or two weeks, according to 98.5 The Sports Hub — Brown's role on defense increased.

Belichick was pleased with the way Brown handled the extra responsibility.

"All of our practice squad players are really told to be ready every week, and they could get called up at any point in the week up until Saturday," Belichick said. "So they all prepare as if they have an opportunity to play, and then if it doesn’t happen, then they start again next week. Sergio has been doing that now the first five weeks, six weeks, including the bye, and with Page's injury and his unavailability for this game, we felt like we could use a little more depth at the safety.

"Unfortunately, Patrick wasn’t able to finish the game, so we really did need [Brown]. We were down another safety. But he did a good job. Sergio did a good job. He stepped up and played a lot more than I think he thought he was going to play, or that we thought he was going to play. He played on defense, played on special teams, played a couple different positions there. I thought he played a solid game. [He] wasn’t perfect. There's a lot of things he'll learn from. He made some good plays. He definitely helped us. I'm glad we had him."