Only a few innings earlier, he had converted another backhanded stop into an impossible force at second, underhand-flipping the ball with uncanny precision to Akinori Iwamura.
But this time, his short-hopped throw was impossible for first baseman Carlos Pena, and as the ball skipped past the bag, Youkilis carried the inevitable winning run down to second.
"I was just running as hard as I could," said Youkilis. "You never know what's going to happen in this game and you've got to run hard. That was just the case. We were very fortunate the ball hopped up and went into the stands."
Given the Red Sox's unstoppable momentum, that play had Game 6 written all over it.
"Of course, you don't want to make blunders like that," Longoria said in the hushed -- but hardly crushed -- Rays' clubhouse, "and put your team in that situation."
The potential for calamity was soon realized. With left-hander J.P. Howell on the mound, Tampa Bay manager Joe Maddon ordered righty-hitting Jason Bay intentionally walked to bring up left-handed J.D. Drew.
Drew won that battle of initials, ripping Howell's 3-and-1 pitch over right fielder Gabe Gross' head for the single heard all around Red Sox Nation.
"It's a tough thing to swallow right now," Longoria said after the Rays' 8-7 loss in Game 5 of the American League Championship Series. "I made a good play picking it, and I got lackadaisical with the throw and didn't put enough on it.
"I had a good grip on it -- just got lazy and threw it in the dirt. Anytime you make an error in the postseason, it's going to be magnified."
After playing errorless ball through their first seven postseason games, the Rays have committed four errors in the last two games.
Three of them have been by Longoria. Although Youkilis was credited with an infield single, Longoria was assessed a throwing error for putting him on second.
But it didn't matter how he got there. By then, given the emotional swing of the game, there seemed little suspense that someone would get him home.
Drew, who has ice coursing through his veins and whose eighth-inning two-run homer had turned what once was a blowout into a one-run game, was a good candidate to do it.
"I got a ball in the middle of the plate," Drew recalled, "and just tried to square it up, hit in in a hole somewhere. I thought I'd hit it well enough to get it over [Gross'] head."
He thought right.
"We've still got two games left," Longoria said. "It'd be a different story if this was the way the whole thing went down, and we weren't getting to the World Series because of this.
"We've got to swallow this, refocus, and come back out Saturday excited about winning a game."