It's called the "Superclasico," the showdown between Buenos Aires rivals Boca Juniors and River Plate, Argentina's two best known clubs.

The passion and the threat of violence will be there again when the teams meet on Sunday at River Plate's Monumental stadium. Both sides lack big-name stars and neither is a real title contender in Argentina's first division.

It doesn't matter. This is a game apart, and winning it is like taking the league title. Boca coach Cesar Falcioni and River's Matias Almeyda are both under increasing pressure, and a loss will only make it worse.

River Plate defender Gabriel Mercado may return on Sunday, 45 days after tearing ligaments in his right knee. No holding back.

"If I have to go all out against Boca and test the knee, I will," he said. "I won't hold back at all. I hope the knee can take it. Everybody is waiting for this match, not just players at River and Boca. I'll put everything into it."

The best-known players for both teams are at the end of their careers, like River Plate forward David Trezeguet. The 35-year-old, who was born in France but grew up in Buenos Aires, is playing in Argentina after winding down as a star with Juventus and the French national team.

He is likely to partner Uruguay's Rodrigo Mora up front. Boca, which counters with Santiago Silva and Lucas Viatri, has suffered since midfield playmaker Juan Roman Riquelme left the team after last season.

Like other Argentine clubs, River and Boca have many older players, many very young players but are missing a core in the middle that has left to play for high-profile clubs in Europe. Players like Carlos Tevez once shined for Boca, and Radamel Falcao for River. Both are long gone, and followed by dozens of other top-draw Argentine players.

"In Europe the game is more fluid, quicker and more tactical," Trezeguet told the daily Clarin newspaper. "The Argentine game is bit more technical but slower because of the conditions of the pitches. And the teams are made up of lots of young kids."

Without star players to focus on, the attention turns to Falcioni and Almeyda.

Falcioni is under the most pressure. Despite winning a recent league title and reaching the final of this year's Copa Libertadores, Falcioni is unpopular with most Boca fans. He canceled a post-game news conference last weekend after a 0-0 draw at La Bombonera against Estudiantes and was jeered when he left the field.

Boca has picked up only two points in its last four matches and has 17 points, two ahead of River with 15.

Newell's Old Boys lead with 23.

Almeyda coached River last season and returned it to the first division after being relegated in June 2011. Lodged in the middle of the standings, relegation is always a possibility again.

Almeyda, who has expressed a desire to coach in Italy, has also been making headlines for other reasons. In a recently published book — "Almeyda: Life and Soul" — he claimed he was given what he believes were drugs when he played in Italy for Parma from 2000-02.

He also said that Roma players asked their Parma counterparts to throw a decisive match between the two clubs at the end of the 2000-01 season. Roma won 3-1 and edged out Juventus for the Serie A title.

River and Boca have not played each other in a competitive match in 17 months, though they did play two friendlies in January and Boca won both.

The record over the last 19 competitive matches is nearly even. Boca has won seven, River has won six, and six were draws.

River has the edge in league titles with 33, followed by Boca's 24.


Follow Stephen Wade at http://twitter.com/StephenWadeAP