The Chargers (2-2) blew late leads in their two losses. On Sunday, they scored the final 20 points to beat Dallas (2-2).
"I feel in sync. I have a rhythm and I'm comfortable in the pocket when we get that no-huddle going," Rivers said. "It's big being 2-2 instead of 1-3. I know we've been there before but it's tough to dig yourself out of 1-3, especially when you're playing with young guys and guys you didn't expect to be in there. They can gain confidence off games like this."
Rivers completed 35 of 42 passes, his final TD pass, to Gates, being the 200th of his career. He threw two TD passes to running back Danny Woodhead.
After having three 400-yard games in his previous nine seasons, Rivers has two in this year's four games.
Rivers' 83.3 percent completion rate was the highest in NFL history for a 400-yard passing game. The previous mark was 81.8 percent (36 of 44) by San Francisco's Jeff Garcia against Chicago on Dec. 17, 2000.
After 35 interceptions the past two seasons, Rivers has been picked off only twice so far while throwing 11 touchdown passes.
"It was really what he did throughout the ballgame," Dallas coach Jason Garrett said. "He did a fantastic job. He really controlled the football and controlled the game. He did an outstanding job getting them into the right play over and over again.
"He threw the ball as well as he's thrown in a long, long time."
Rivers' biggest pass wasn't necessarily his prettiest. He short-armed one over the middle to Gates, who slid behind linebacker Sean Lee to haul it in and score with 6:54 to go.
Lee had intercepted Rivers on a deflected pass and returned it 52 yards for a 21-10 lead late in the second quarter. Dallas didn't score again.
"We were able to get some looks we thought we could take advantage of," said Gates, who had 10 catches for 136 yards. "The way he threw that ball, he put it in the right place and I was able to make the play."
"I saw that the ball was a little loose. We learn as a kid you can put a hit on the ball and it comes out," Butler said. "I had no idea he lost it. Then I rolled over and I saw Marshall had it.
"Last week was tough and I had to move on from that," Butler added. "Being a defensive back you have a short-term memory. I'm glad I made that play today."
It was only the second takeaway of the season for San Diego.
San Diego trailed 21-10 when Nick Novak started the comeback with a 42-yard field goal as the first-half clock expired.
The Chargers took the opening kickoff of the second half and Rivers moved them 80 yards, capping the drive with a 13-yard pass to Woodhead to pull to 21-20.
The way Rivers ran the offense, the Cowboys didn't have a chance to come back. They ran only seven offensive plays in the third quarter.
"That's what we see every day," Woodhead said of Rivers. "He was great, but he's always great."
After forcing Dallas to punt, San Diego took a 23-21 lead on Novak's 23-yard field goal that capped a drive starting from the Chargers 11.
Romo threw touchdown passes of 5 and 34 yards to Dez Bryant in the second quarter, when Dallas scored 21 points.
Lee got his interception return for a TD when Rivers was hit by tackle Jason Hatcher as he released the ball.
NOTES:Chargers LB Manti Te'o made his NFL debut. He'd been out since spraining his right foot in the exhibition opener Aug. 8. ... Chargers OLB Dwight Freeney hurt a quad in the second quarter and didn't come back. ... Woodhead had two TDs receiving in a game for the first time in his six-year career. He also had a 26-yarder in the first quarter.
Copyright 2013 by The Associated Press