But, at that pivotal moment, Nick Foles was taking his first 2013 snap, and Vick, a prisoner of the new NFL, was taking an unwanted eight count.
In a league now as conscious of concussions as TV ratings, an official can force a player to the sideline after the kind of head-rattling jolt Vick endured on Jarius Wynn's body slam a play earlier.
That's what happened, and Vick, even though he insisted his head was as clear as the crystalline South Philadelphia afternoon, had to stand and watch the pivotal play.
"I was back up and standing and ready to play," Vick said afterward of the second down. "The referee told me I had to come out. . . . If I'm standing up, I'm not hurt. I'm ready to go.
"But he said I had to come out for a play. That was unfortunate for my team. But, hey, they're doing their job, and I won't try to negate any decision they make."
Foles' first pass of the season, to DeSean Jackson, followed and was uncatchable. Vick ran eagerly back onto the field, but with the Chargers geared for a pass, threw an incompletion of his own.
"Mike was hit hard, but he seemed fine when he came back in there," said Jason Avant, the target of Vick's final pass on that drive. "It was just one of those plays where they knew we were going to throw the ball."
An Alex Henery field goal made it 30-30. And with a comfortable 1:55 in his quiver, Rivers engineered the inevitable game-winning drive against an Eagles defense that had no answers. San Diego's 51-yard, nine-play drive ended with 11 seconds left on Nick Novak's 46-yarder.
The disappointing ending couldn't obscure a second superlative performance by Vick, who already has thrown for 631 yards and four touchdowns without an interception.
So efficient has he and Chip Kelly's offense been, swallowing up big gulps of yardage in single plays, that they're leaving far too much time for opponents.
"They did a good job of controlling the football," Vick said of the Chargers. "They kept us off the field and out of rhythm in the first half. In the second half, we were able to get in a rhythm and score 20 points."
Chargers coach Mike McCoy said his team understood the Eagles would generate some big plays.
"That's the way they play the game," he said. But he also was confident they could march up and down the field.
After a sputtering start, Vick matched and may even have surpassed Rivers, whose 124.3 rating was built on 36 completions for 419 yards and three touchdowns.
He was as accurate as he's been as an Eagle. He found Jackson for a 61-yard TD, and the duo easily could have had three more long scoring connections.
On one bomb, Jackson's second foot landed out of bounds when it appeared it easily could have stayed in. Another long touchdown pass to the little wideout was negated by a penalty. And, finally, a perfectly thrown deep ball to Jackson bounded off his fingertips.
"Obviously it wasn't enough," Vick said of his day. "We wish we could go back and do some things differently. . . . We can't hang our heads over what should have happened. We should have made it happen."
In the end, as the Eagles face a third game in 11 days on Thursday, there has been one lasting impression from their first two: If they're going to dream of the playoffs, they're going to have to outscore an awful lot of opponents.
"Coach Kelly did a great job of making adjustments throughout the course of the game with the play-calling," said Vick.
"It's tough," he added. "Maybe we need to score 37 points."
Comparing the QBs
Comp./Att. Yds. Avg. TD Int. Rating
Philip Rivers 36/47 419 8.9 3 0 124.3
Michael Vick 23/36 428 11.9 2 0 123.4
In the Clutch
Vick has directed 13 fourth-quarter comebacks and 14 game-winning drives, three coming in 2012.
Rivers has engineered 13 fourth-quarter comebacks and, including Sunday's game, 17 game-winning drives, his previous coming in 2011.
Contact Frank Fitzpatrick at email@example.com. Follow @philafitz on Twitter.