SAN DIEGO -- On the surface, it wouldn’t seem to be the matchup that the Patriots wanted: rookie safety Sergio Brown on Chargers All-Pro tight end Antonio Gates.

That’s how it unfolded on a crucial play on the Chargers’ final drive.

With the Patriots’ defense looking to hold on to a 23-20 lead, San Diego had the ball on the New England 35. It was third-and-10 with 1:14 remaining.

Quarterback Philip Rivers found tight end Antonio Gates short to his right, and Brown wrapped him up for the tackle, two yards short of the first-down marker.

Huge play.

The Chargers had to settle for a field goal, and they ended up self-destructing.

As for Brown, he had been on the Patriots’ practice squad for the first six weeks of the season and was promoted to the active roster this past Saturday.

“I really couldn’t [write a better script],” he said after the game. “It felt wonderful. They taught me how to play defense and I was just doing what I was supposed to do -- being in the right position at the right time.”

Brown was active for the game because veteran Jarrad Page is sidelined with a calf injury, and his primary contributions were expected to come on special teams. But when safety Patrick Chung was knocked out of the game with a knee injury in the first half, Brown came on the field in defensive sub packages.

The big tackle on Gates came with the Patriots in their dime package (six defensive backs).

“I was just ready for any opportunity to come up,” said the former Notre Dame defender. “Once it came up, I was just playing hard, the only way I know how to play.”

Teammates lauded Brown's performance, as did the coaches.

“The staff does an excellent job as far as grooming talent and getting guys ready to play,” linebacker Jerod Mayo said. “Everybody on the practice squad, they know at any given time their number might be called to play. He came up and played well.”