"Philip just opens up everybody," receiver Malcom Floyd said. "We've got all kind of weapons on the field. It's pretty much just picking your poison."
A week after throwing three touchdown passes to Gates in a 30-21 win over Seattle, Rivers turned his attention to several other targets in completing 18 of 25 attempts for 256 yards. Floyd had two 49-yard catches that set up separate scoring drives. Royal finished with four catches for 42 yards, and backup tight end Ladarius Green had four catches for 64 yards.
"It's key, no matter who's in there," said Royal, who scored on 3- and 5-yard touchdown catches. "It's great when you've got a lot of guys that can make plays."
The Chargers even overcame the loss of another running back a week after starter Ryan Mathews sprained his right knee. Against Buffalo, Danny Woodhead did not return after hurting his right ankle on his first carry 3½ minutes in.
Donald Brown stepped in and finished with a combined 89 yards offense (62 rushing and 27 receiving).
Coach Mike McCoy did not have an immediate update on the severity of Woodhead's injury except to say the player was going to have more tests.
Rivers, however, indicated he expects Woodhead to miss at least a few weeks.
The Chargers are off to a 2-1 start for the third time in four years. And they built on the momentum generated following a 30-21 home win over the defending Super Bowl champion Seahawks.
Fred Jackson scored on an 11-yard catch and run for Buffalo (2-1), which blew an opportunity to get off to a 3-0 start for only the third time since 1993.
Quarterback EJ Manuel went 23 of 39 for 238 yards, but had difficulty finding chemistry with his receivers.
"We weren't in sync," Bills coach Doug Marrone said. "There's a lot of things that we can learn from this game, and we've got some young guys out there and they'll continue to get better."
A week after catching eight passes for 117 yards and a touchdown, rookie receiver Sammy Watkins was limited to two catches for 19 yards despite being targeted eight times.
There were several times when Watkins short-armed throws his way. Another time, he was late turning for the ball, which sailed past him on what was a costly incompletion. It came on fourth-and-3 at the Chargers 43 with 8:25 left.
"Just throwing the ball a hair too soon," Manuel said. "I wouldn't say it's a wake-up call, but it's definitely something that's needed to get us back into that groove of winning."
Manuel also gave up a safety after being penalized for intentional grounding in the end zone with 3:23 remaining.
The Chargers defense had three sacks and limited the Bills to 11 first downs and 171 yards of offense through three quarters.
San Diego took control on consecutive possessions spanning halftime.
Nick Novak capped a seven-play, 61-yard drive with a 37-yard field goal to put the Chargers up 13-3 with 21 seconds left in the second quarter.
Rivers opened the third quarter by marching the Chargers on a 14-play, 80-yard drive, which he capped with a 5-yard pass to Royal. Rivers completed four of six attempts for 56 yards on the drive, and converted all three third-down chances.
"We were tired of getting field goals," Royal said about ending the drive with a TD. "It's great to get points, but we wanted to score a touchdown."
The Bills were unable to muster a threat after Jackson cut the Chargers' lead to 20-10 late in the third quarter.
Buffalo's next drive ended with Corey Liuget sacking Manuel for a 17-yard loss, and the next ended on downs with the incompletion to Watkins.
And the sold-out house began heading for the exits with 5:31 left when defensive end Kendall Reyes sacked Manuel for a 10-yard loss to force a punt on fourth-and-20 at Buffalo's 10.
Novak also hit a 19-yard field goal, and extended his streak to hitting 23 straight attempts to pass Nate Kaeding for second on the team list. ... Andre Reed was honored during a ceremony at halftime, when he was presented his Hall of Fame ring by Pro Football Hall of Fame President David Baker. Reed was one of seven to be inducted into the Hall of Fame in August. ... Bills LG Chris Williams (back), WR Marcus Easley (left knee), S Da'Norris Searcy (ankle) did not return after being hurt.
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