ORCHARD PARK — Philip Rivers threw for two touchdowns and San Diego’s defense recorded three sacks and a safety as the Chargers defeated the Buffalo Bills 22-10 Sunday afternoon at blustery Ralph Wilson Stadium.

The Chargers improved to 2-1. The Bills dropped to 2-1.

Rivers completed 18 of 25 for 256 yards and wide receiver Eddie Royal caught touchdown passes of three and five yards as the Chargers improved to 2-1.

The Bills, who were limited to 87 rushing yards — 76 below their average — dropped to 2-1.

The Chargers took a 7-0 lead on a 3-yard touchdown pass from Rivers to Royal with 9:45 left in the first quarter. The big play in the seven-play drive was a 49-yard bomb from Rivers to wide receiver Malcolm Floyd that advanced the ball to the Bills’ 24.

San Diego improved its lead to 10 on Nick Novak’s 19-yard field goal. The 17-play, 91-yard drive was aided by two defensive penalties and saw Rivers complete passes of 23 yards to Royal, 13 yards to running back Donald Brown and 20 yards to tight end Ladarius Green.

The Bills broke into the scoring column on a 45-yard field goal by Dan Carpenter with 2:56 remaining in the half. The kick capped an eight-play, 65-yard scoring drive that featured a 21-yard catch and run by running back Fred Jackson and a 37-yard completion from EJ Manuel to tight end Scott Chandler.

San Diego answered with a 37-yard field goal by Novak with 21 seconds left in the half. The big play in the seven-play, 61-yard drive was a 49-yard completion from Rivers to Floyd.

The Chargers drove 80 yards in 14 plays in their first series in the second half and went up 20-3 on a 5-yard touchdown pass from Rivers to Royal. Rivers had completions of 14 and 26 yards to Green on the drive.

Buffalo closed the gap to 10 with 1:16 left in the third on an 11-yard touchdown pass from Manuel to Jackson. Manuel completed 4 of 5 passes for 40 yards and also had an 8-yard scramble on the drive.

San Diego picked up a safety with 3:23 left in the game when defensive end Corey Liuget pressured Manuel in the Bills’ end zone and the second-year quarterback threw the ball away to an area where there wasn’t a Buffalo receiver.

NOTES: Mike Scifres had a wind-aided, 72-yard punt for San Diego in the early fourth quarter. … Chargers RB Danny Woodhead, who had started in place of injured Ryan Mathews, was carted off with a sprained ankle three minutes and 23 seconds into the first quarter and did not return. … Dwight Freeney, who replaced injured outside linebacker Mel Ingram in the San Diego lineup, recorded the 110th sack of his career. … Bills all-time leading receiver Andre Reed received his Pro Football Hall of Fame ring during halftime ceremonies.