New coach Gerardo Martino has drafted the duo into the squad as he prepares to lead Argentina into a rematch of the World Cup final at the Esprit Arena in Dusseldorf.
Martino has been hit by the loss of a number of key players, including Barcelona superstar Lionel Messi, who has pulled out the squad as a precaution due to a hamstring strain.
Maxi Rodriguez is also out with a similar problem, while Rodrigo Palacio (ankle) and Ezequiel Garay (thigh) are also unavailable.
Paris Saint-Germain forward Ezequiel Lavezzi is also a doubt with a back complaint, leaving Martino with little choice but to bring in reinforcements.
Neither Benfica attacking midfielder Gaitan nor Tottenham forward Lamela featured at the World Cup, with the former now in contention to win his first cap since a 2-1 defeat to Poland back in June 2011.