Real Madrid agreed to sign the highly-rated 20-year-old Argentine midfielder from Boca Juniors on a six-and-a-half-year contract.
Argentina midfielder Fernando Gago could miss the World Cup due to a knee injury after his club Boca Juniors said on Monday he would need up to 60 days to recover.
Renato scored a late winner for Sevilla at the Bernabeu as they survived a spirited fightback from champions Real Madrid to win 4-3 in the Spanish Primera Liga on Sunday. Adriano Correia gave Sevilla a third-minute lead and although Raul pulled one back in the 19th minute, Ndri Romaric and Frederic Kanoute had the visitors 3-1 up at halftime.
Real Madrid defender Roberto Carlos said the pitch was responsible for the mistake that allowed Bayern Munich to take the lead after 10 seconds of their Champions League game on Wednesday.
Angel Di Maria and Sergio Aguero will miss Argentina's final South American World Cup qualifier against Uruguay on Tuesday as the team who have already booked their place at next year's finals prepare to field yet more reserves.
Striker Sergio Aguero, injured during Argentina's shock 2-0 home defeat by Ecuador in a World Cup qualifier, said on Friday he would be out for a month.
Argentina have reached three major finals in three years but the team who came so close to winning the 2014 World Cup face crunch games against Peru and Ecuador that will determine if they miss out on the global showpiece event for the first time since 1970.
Summary of the South American World Cup qualifiers played on Thursday