The option to replace Gasquet, who has a foot injury, with Simon shows the depth of French tennis. Simon is ranked 13th in the world and France's Jo-Wilfried Tsonga, who was installed in the key lead-off singles position for Friday, is No. 8 in the world.
The best-of-five series is to be contested on an outdoor clay court in Buenos Aires, with two singles matches Friday and Sunday and a doubles match Saturday.
The winner moves to the Davis Cup semifinals against either defending Davis Cup champion Czech Republic or Kazakhstan.
The French doubles team of Julien Benneteau and Michael Llodra goes against Argentines David Nalbandian and Horacio Zeballos on Saturday. Sunday's reverse singles has Monaco playing Tsonga first and Berlocq meeting Simon in the finale.
France is 5-0 all-time in the Davis Cup against Argentina, with the most recent meeting coming in the 2010 semifinals. The French have won nine championships. Argentina has never won the Davis Cup but has been the runner-up four times, including in 2011.