The burly, shaven-headed Uruguayan nickname El Tanque (the tank) has been allowed to join Boca's squad in the championship despite FIFA regulations stating that a player cannot turn out for three clubs in one season. He has already played for Velez Sarsfield and Fiorentina.
The Argentine Football Association (AFA), however, were given the go-ahead by FIFA to make a decision and voted in favour of granting Boca their wish to name Silva as a replacement for winger Nicolas Colazo, who broke his leg last weekend and will be out for the rest of the season.
Boca vice-president Juan Carlos Crespi, asked why FIFA regulations appeared to have been overlooked, told TyC Sports that football's world governing body "told AFA they could make the decision".
The AFA board, headed by powerful FIFA vice-president Julio Grondona, voted almost unanimously in favour of Boca's request.
The 31-year-old Silva was at Velez when the Argentine season began in August but was signed by Fiorentina before the mid-year transfer window closed. He saw little action in Serie A and signed for Boca in the January window with the proviso that he was allowed to play for them only in the Libertadores Cup.
Boca argued that they could not sign a replacement for Colazo because the transfer window was now closed.
Boca will be defending a 32-match unbeaten run in the league (35 in all competitions) at the Nuevo Gasometro, where San Lorenzo have not won since they beat Tigre in early December in the Clausura championship.
The Saints, or Cyclone as the team with red-and-blue stripes are also known, are fighting to avoid relegation and won for the first time in five matches at Argentinos Juniors last weekend.
Racing Club, who have made a disappointing start to the season's second championship, will be without controversial Colombia striker Teofilo Gutierrez, sent off in the shock 2-1 home defeat by Banfield, for Sunday's trip to Arsenal.
Coach Alfio Basile also has problems with team captain Claudio Yacob, who refused to sit on the bench last weekend after being dropped and has been suspended from the squad.
After three matches, the Clausura is led jointly by Boca, Velez, Tigre and All Boys, who all have seven points.
