Real Sociedad forward Carlos Vela is to undergo surgery after suffering a torn meniscus in Saturday's 4-1 defeat at Real Madrid.

Mexico international Vela had to be substituted after 17 minutes at the Bernabeu and is reportedly likely to miss at least six weeks for David Moyes' side, who are currently four points clear of the relegation zone.

A statement on La Real's official website on Monday read: "During the match held in Madrid he suffered an injury to his right knee. After early tests, labs and an MRI, we have found evidence of a torn meniscus. After consulting with specialists to evaluate the best therapy options, we have decided on surgery.

"Carlos will be operated on today by Dr. Mikel Sanchez. Once the surgery is complete we will issue a new medical statement."

Following Saturday's game, Moyes had suggested that Vela's injury had added to his frustration at failing to bring in his targets prior to the end of the transfer window in Spain.

"Carlos Vela is a super player, very important for us," he said of a striker who has scored five of Sociedad's nine goals in La Liga since Moyes took charge in November. "We were disappointed not to make some purchases in the January window.

"We tried very hard, but we hope the injury is not too bad. Someone else will get a chance to show what he can do, if he is injured."

Vela will hope to be back to full fitness in time to help Sociedad in La Liga and to play for Mexico at the CONCACAF Gold Cup, which begins on July 7.