Barcelona's goalkeeper Victor Valdes takes part in a training session at Joan Gampar training camp, near Barcelona in this February 14, 2014 file photo. [Photo/Agencies]

MANCHESTER, England?- Manchester United signed former Barcelona goalkeeper Victor Valdes on Thursday as a backup to fellow Spaniard David de Gea.

The 32-year-old Valdes, who has been at United training with the first team since October while rehabilitating from a knee injury, signed an 18-month contract, with the option for a further year.

"He joins the club as the No. 2 goalkeeper and is a great addition," United manager Louis van Gaal said.

Valdes, who tore the anterior cruciate ligament in his right knee in March before being released by Barcelona, won every major honor with the Catalan giant, and the 2010 World Cup and 2012 European Championship with Spain.

Valdes is preparing to fight for his first-team place at United.

"Now, in the moment, (De Gea) is the best goalkeeper in the world," Valdes said. "His performances every day and in every game shows everybody that his level is very high. He has had a great year."

Valdes' signing is likely to increase the chances of the 30-year-old Anders Lindegaard leaving the club in January. United's other goalkeeping options are 21-year-old Sam Johnstone, who is on loan at Doncaster, and 24-year-old Ben Amos.