Randy Moss' flip to Moe Williams swung momentum to the Vikings going into halftime. AP

MINNEAPOLIS -- The moment was pure sandlot. A play so improvisational that it could have been drawn up in the dirt with a stick on the playground rather than diagrammed on a grease board in marker.

And still, Randy Moss somehow knew what he was doing in the midst of being spontaneous, instinctive and entirely unconventional. It's hard to practice spur-of-the-moment genius, but every Saturday, at the end of the team's walk-through workout, Moss and his offensive teammates do just that.

On Sunday, in the most remarkable fashion, it paid off, as the Minnesota Vikings stunned the Denver Broncos with another Moss original on the final play of the first half. The miracle touchdown -- a 44-yard Moss reception followed by an over-the-shoulder, no-look lateral to running back Moe Williams, who took it 15 yards for the score -- didn't just stand as the difference in the Vikings' 28-20 victory; it may end up standing as one of the defining masterpieces of Moss' never-know-what's-next career.

With apologies to Robert F. Kennedy, some players see plays as they are and ask, why? Moss see plays that have never been and asks, why not?

"It's a once-in-a-lifetime thing that happens every so often,'' said Moss, showing he's as deft with a malaprop as he is with the football. "I don't want to call it luck, because we work on that play.''

The 59-yard touchdown, which came with the first-half clock expiring on the play, gave the sagging Vikings a 14-7 halftime lead and reversed the game's momentum, which had swung Denver's way late in the second quarter. Credit Moss once again with being undefeated Minnesota's biggest difference maker.

Asked if he had ever seen a play like Moss', Broncos receiver Rod Smith summed up everyone's sense of wonder: "Yeah, on PlayStation. That's what he is and who he is. That's why he makes all the money that he makes. You just have to take your hat off to a guy who makes plays.''

As recently as Saturday, Moss' famed creativity failed him. At the end of practice, he tried the hook-and-ladder that did in the Broncos and couldn't execute.

"Randy did it on Saturday, and he kind of puttzed around and missed Moe,'' Vikings center Matt Birk said. "The ball ended up on the ground. I said, 'Way to go, Moss, you just lost the game for us.' That's a true story.

"In practice, he usually just catches the ball with no one around him, but then today he's got two guys hanging on him, he's falling forward, and he throws it over his head and puts it right on the numbers. I guess we're making things too easy on him in practice. He needs to be challenged a little bit.''

The play that everyone can't stop talking about unfolded as a third-and-24 from the Vikings 41, with 12 seconds remaining in the first half. Minnesota quarterback Daunte Culpepper took the shotgun snap, rolled right, away from pressure, and near the line of scrimmage let the ball fly for Moss about 50 yards downfield.

Despite being covered by Denver safeties Nick Ferguson and Sam Brandon, Moss came back for the ball and caught it with just one second left in the half. Immediately wrapped up by the two defenders near the Broncos' 14, Moss, in the process of going down, blindly flipped the ball back over his shoulder in the direction of Williams. The running back caught it in stride and scooted untouched into the end zone, as the disbelieving Broncos looked on.

"You have got to be kidding me!'' Denver head coach Mike Shanahan said. "It was a great play by a great athlete. He did what a great athlete does. He made a play.''

Moss, who finished with 10 catches for a game-high 151 yards receiving, made a play that even his head coach discourages his working on in practice.

"What he did was improvisation, but goofing around, the [guys] at the end of practice Saturday do that,'' said Vikings head coach Mike Tice, whose 6-0 team is one of the league's final two undefeated squads. "I don't particularly like it that much, but you can't take all the fun out of the game. So they do it all the time in practice, and I roll my eyes and cringe when they do it. But I guess I'll let them keep doing it.

"Sandlot football is for the street. But sometimes you get away with a sandlot play, and that's what it was. It was great improvisation by two heads-up players. It was a lot of fun.''

Know this much: Moss' big moment against the Broncos will wind up on everyone's play-of-the-year short list. In his six seasons, Moss has caught touchdown passes, thrown touchdown passes and returned a punt for a touchdown. Now he's lateraled for a touchdown pass, too, at the most opportune time. Let's face it, No. 84 is running out of ways to wow us.

More and more, we're coming to the realization that the NFL is his world and the rest of us are just allowed to watch.

"If Moe Williams isn't hustling and if Randy wasn't the phenomenal player he is and had the awareness he has, then that play would never happen,'' said Culpepper, who took a huge hit on the touchdown pass and didn't see Moss' inventive play. "And you never know when it's going to happen, when the time's going to come when a play like that is going to work. But it happened today.

"You can't teach what happened on that play. But I'm always going to pop back up when something that beautiful happens. That's sweet. That's saucy. We call it 'saucy.'''

Williams said he and Moss made eye contact as soon as Moss caught the ball and that he started yelling for the lateral. "I was just yelling, 'Moss, Moss, Moss!' as I was coming down,'' Williams said. "He didn't yell anything back; he just threw me the ball.

"When we try it in practice, coach Tice always tells us to secure the ball and get down. All that type of stuff. Good thing we didn't listen this time.''

Moss said many times in practice, his attempted laterals get picked off by Vikings cornerback Denard Walker. But this time, when it really mattered, his play caught his opponent by complete surprise.

"I didn't really get to see Moe coming,'' Moss said. "I saw a jersey coming, and it happened to be the color I had on. I didn't really know who I was pitching it to. I just saw a Vikings jersey and I just threw it behind my back.''

Even the officials couldn't really believe what they had witnessed from Moss, because the play was challenged and reviewed by the replay booth, coming as it did in the final two minutes of the first half. But Williams clearly caught the ball behind Moss, making it a legal play. And one that probably wouldn't have happened last year for the Vikings, when they started 3-10 en route to a 6-10 finish.

"It's true, when it rains it pours, and when you're winning, everything seems like it works,'' said Culpepper, who returned to the lineup Sunday after missing two and a half games with broken bones in his lower back. "It happens like that.''

It did on Sunday in the Metrodome. And because of it, the legend of Randy Moss has added another unique chapter.

Don Banks covers pro football for SI.com.