Gloves off in the Vicente Calderón

"He's lacking a bit of playing time, but we're talking about Leo so it doesn't really matter," said Barcelona coach Gerardo Martínez of his number 10 ahead of Wednesday's King's Cup match against Getafe. The Argentina captain had spent two months out of action with a hamstring injury and was named among the substitutes for the match. Hopping off the bench, Messi proceeded to score two goals in three minutes to take the scoreline to 4-0 and practically assuring Barcelona's passage to the next round of the competition.

The timing of Messi's return could not be better for Barcelona: this Saturday a top-of-the-table clash at the Calderón (8pm, Canal+) will pit the joint league leaders against each other for the first time this season in a test of Atlético Madrid's title aspirations. Diego Simeone's industrious side took three points from Real Madrid's Bernabéu home for the first time in 14 seasons earlier in the campaign, adding to its cup triumph on the same stage in May, a victory that ended a winless streak stretching back to that 3-1 league win in 1999.

Lifting last year's King's Cup afforded Atlético the chance to face league champion Barcelona over two legs in the Spanish Supercup at the outset of this season in another gauge of the Simeone effect. The Argentinean, who marshaled the midfield when Atlético last won the league title in 1996, arrived at the club two years ago and his since then fashioned a formidable unit that this season has conceded fewer goals than any other team and been beaten just once. Barça's numbers are identical: played 16, lost one, tied one.

Only goal difference separates the two, and if they are still neck and neck at season's end — the two sides will meet on the last day in Camp Nou — head-to-head results will decide the title. If that is also all-square, then goal difference will come into play. It is fair to say this is the biggest match of the season so far, and Atlético can certainly allow itself a wry smile that for once it is taking place in the south of the capital.

Leo Messi has hit 20 goals against Atlético, including three hat-tricks

It is the neoclásico: a return to a time when the Spanish league was not just a tango for two.

Despite Messi's absence, Barcelona has been keeping pace and scoring fairly freely. But if both sides could choose to remove one player from the other's ranks the debate would be brief. Messi has an unerring knack of scoring against Atlético: a nice round 20, including three hat-tricks.

In Atlético's armory, Diego Costa is the danger man: 19 league goals so far this season, although he is ably supported by former Barça striker David Villa and a glut of goals from midfield, especially from the boots of Raúl García.

But the prowess of both sides — 100 league goals between them in 18 rounds of fixtures — does not portend a cricket score in the Calderón. In the Spanish Supercup, they shared just two in 180 minutes of Camp Nou and Calderón action, with Barcelona proclaimed champion on the away goals rule. However, the oppressive heat of an Iberian August played as much a part in those games as the two sides were able to endure.

"It will be a fist on the table if we can beat Atlético," said Barcelona veteran Xavi, describing the match as "vital, but not definitive."

The winner of the clash will assume the title of "winter champion," a peculiar Liga rite. Neither will care particularly. If both are in the same position on the weekend of May 17 and 18 as they are now, then that encounter will be definitive. Saturday's match is merely a marker. Both will drop points in the second half of the season; what is of vital importance for Atlético and Barcelona is not to surrender three in the Calderón.