For the sake of both its honor and its hopes of ending a four-year La Liga title drought, Real Madrid just needed not to lose the final Clasico of the season against Barcelona in Madrid on Sunday.

Barca needed the win. With the remaining games in the La Liga season ticking down to a handful, it needed to snag all three points amid the animosity of the Bernabeu in order to equal Real atop the table. Real, after all, has a game in hand. And a six-point gap, with Real positioned to make it nine, would have been insurmountable.

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A Lionel Messi winner on the final play of the game, following a late apparent equalizer by Real’s James Rodriguez with his team reduced to 10 following Sergio Ramos’s expulsion, locked up the points in a whipsaw game. Barcelona came back from a Casemiro opener with tallies by Messi and Ivan Rakitic before James evened things up again to seemingly retain the status quo in the standings.

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But Messi would have the final say. And his winner in a 3-2 victory was, fittingly, his 500th goal for the club.

In truth, the contest could have swung either way – and it did several times. Both teams certainly created enough chances to score double-digit goals. It was an immediately memorable edition of the Clasico for its endless chances, bounty of magnificent saves by Keylor Navas and Marc-Andre Ter Stegen and nonstop drama.

A helter-skelter game began, appropriately, when Cristiano Ronaldo was denied a penalty just 90 seconds in. In the box, he tapped a ball just out of the reach of Samuel Umtiti and was taken out by the French defender. It was a clear-as-day penalty, spared by referee Alejandro Hernandez Hernandez as an apparent courtesy to the early stage in the game.

Real Madrid was indeed the more threatening team out of the gate, thundering forward in numbers on the counter. Ronaldo forced a strong save out of Ter Stegen. And, as if to underscore the way the game was going, Real left back Marcelo clocked Messi in the mouth on an aerial challenge, turning his mouth into a bloody mess.

It should probably have been a red card. But it was no card at all.

Real pressed so high that it even unsettled the veteran Barca defender Gerard Pique, who implored his teammates to settle down. But the Catalans had to go behind before they could get their act together.

In the 28th minute, Marcelo sent a cross into the fray and found Ramos. He had stayed onside by inches and kissed his volley off the near post. It bounced into the path of Casemiro, who coolly but acrobatically contorted the ball into the net.

At last, Barca woke up and began forging paths through Real’s half. Five minutes after Madrid’s go-ahead goal, Sergio Busquets fed Ivan Rakitic. He found Messi hurtling into the box. The Argentine twisted and turned through a thicket of defenders and beat Navas.

It was his first Clasico goal since 2014.

Barcelona would finish the half as the better team, although Luka Modric’s long-range blast required an elegant dive from Ter Stegen. Casemiro, after an early yellow, was fortunate to be spared a second on the brink of halftime when he brought down Messi on a counterattack.

While the sides exchanged chances, Messi had a flying volley tap-in on an open goal gifted to him. But he led with his left foot, when his inferior right might have been the answer, and somehow dinked it wide.

Ter Stegen fairly well stood on his head in the second half, particularly when he denied Karim Benzema’s header on the doorstep from Marcelo’s cross. But then so did Navas. The Costa Rican made big saves on Paco Alcacer and Pique’s header on a corner.

At the other end, and within a minute or so, Ronaldo scooped a great look just over …

… and Navas denied Suarez’s flying blast from nearly point-blank range.

After yet another big Ter Stegen save on Marco Asensio, Rakitic finally rifled in the go-ahead goal for Barca in the 73rd minute.

When Ramos was sent off for an assault on Messi soon thereafter, it seemed to be all over for Real.

So when Pique had a point-blank look, he may well have swung the season. But Navas came up big for the umpteenth time. Pique corrected for his mistake by blocking Ronaldo’s potential equalizer on the break. But James, a substitute, would deliver the goal that Ronaldo failed to provide, dinking home from the Marcelo cross.

But in the final seconds, there would be a last twist. Messi finished off a beautiful team counter by tucking his shot from the edge of the box into the few inches Navas didn’t have covered.

Messi walked over to the stands at the Bernabeu, peeled off his jersey and just held it aloft, for all of Madrid to see his name.

And with that, Barcelona had said enough. And Messi had said enough.

Leander Schaerlaeckens is a soccer columnist for Yahoo Sports. Follow him on Twitter @LeanderAlphabet.