Pérez was taken to hospital with an eye injury but the medical team of Conmebol, the South American federation, released a statement saying neither he nor any Boca player was unfit to play.
The second leg of the 2018 Copa Libertadores between River Plate and Boca Juniors has been postponed due to crowd trouble and safety concerns.
The mood had seemed excited and expectant as River fans descended on the Stadio Monumental, while Boca fans, thanks to the ban on away fans in Argentina, made for their home ground, La Bombonera, eight miles away, to watch on a giant screen.
The attack shattered several of the bus windows and Boca players were cut by broken glass and also suffered from smoke inhalation due to tear gas.
Copa Libertadores final hit by pre-match violence
Carlos Tevez is perhaps the most high profile player involved for either side with the former Man United star a Boca legend but he has certainly been caught up in the panic with pictures of the player being helped into the changing rooms also emerging on social media.
Boca eventually agreed to play, but kick-off was delayed by two and three-quarter hours and it was clear they were playing under protest. "But the truth is we're not in condition to play". It will not be played behind closed doors, which raises the prospect of angry Boca fans making for the stadium to take their revenge.
Clarin said six players had vomited in the dressing-room after gas drifted into bus windows smashed by River fans outside the stadium.
Tevez was interviewed by a local television station and said: "We are not in a position to play the game". Police organise scores of River games every year and know where potential flashpoints are likely to occur. But it is little solace to the supporters who eagerly awaited this showpiece final, in many cases spending thousands of dollars and travelling vast distances to see the action.
The match has been rescheduled for Sunday and will kick off at 5pm local time (8pm GMT). Argentine football has been shamed, tainted nearly beyond fix, and it is hard to see any improvement possible with such criminal incompetence reigning among those entrusted with the organisation and safety of the sport.
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Ant, 43, who is now on holiday in a secret location with girlfriend Anne-Marie Corbett, 42, is expected to return to TV next year. Atack replied "I would love that" and was then seen giving the sign of the cross before sitting down to pray.