Really, McNabb has played in plenty of these, often against the Cowboys.
And he has been magnificent.
First season as a starter? On a bitter December day in Cleveland, McNabb dominated and the Eagles clinched a playoff spot in 2000.
The next season? He was brilliant as they clinched the NFC East title in the Meadowlands, leading two TD drives against the Giants in the last 2 1/2 minutes.
In 2002, he missed the last six games of the season with an ankle injury, then came back for the team's first playoff game and beat the Falcons.
They needed a finale win in Washington in 2003 to lock up a division title and bye, and McNabb thrillingly channeled Michael Jackson.
It was a lost cause in 2007, the Eagles having practically fallen out of the race by late December thanks to McNabb injuries. But down the stretch, he outplayed Tony Romo, then scorched the Saints and Bills.
And, of course, last season's successive miracles after the Game 10 tie (and McNabb's confusion) and the Game 11 benching against Baltimore - well, those were pretty pressure-filled, right? McNabb went 4-1 down that stretch, and was plenty good against the Cowboys in the one that mattered most, the clincher.
His combined passer rating in the eight referenced games: 103.8.
His combined stats: 172-for-279, 2,130 yards, 18 touchdowns, two - yes, two - interceptions.
Sunday's game might matter in McNabb's career portfolio, and a Super Bowl win or two certainly would enhance its value, but, really, he's painted plenty of masterpieces in games like these.
"This game won't define his career. His career is already defined," said veteran Eagles linebacker Jeremiah Trotter, who has been involved in most of McNabb's best pressure games. "The numbers don't lie."
There have been other big games along the way, both before the seasons' homestretches and during the playoffs.
But, to be fair, in games like Sunday's there also has, generally, been a pair of Pro Bowl-caliber tackles with him; a standout running back, whether Westbrook or Duce Staley; and dangerous, star-studded defense.
None of those conditions exists this time.
So, while McNabb might be scrutinized disproportionately for what happens Sunday, really, he's been there before.
That comforts his coach and backfield mate.
"There probably aren't enough words to describe it," Andy Reid said.
"It's great to have Donovan there. He's a guy that we know is going to come up big in the big situations," Westbrook agreed.
Whether he does it again, after a decade of doing it so well in the same city, it should be a moment in his career . . . but not the moment.