Athletic Bilbao have confirmed they will be without Iker Muniain for six to seven months after tests revealed the forward had suffered a cruciate ligament tear in his left knee.

The 22-year-old went down after going in for a challenge with Sevilla’s Ever Banega during Bilbao’s 2-0 defeat on Saturday.

Muniain was then taken from the field on a stretcher and had been hoping the injury was sprain.

Unfortunately, the diagnosis could not have been worse.

The forward will now miss the Copa del Rey final against Barcelona on May 30, and will likely be sidelined for the start of the 2015-16 campaign.

Manchester United midfielder Ander Herrera, who played alongside Muniain for three seasons, sent his friend a message via social media when news of the injury first broke.

The former Athletic Bilbao playmaker posted the following words to his official Instagram account: “With you more than ever my friend, football will miss you these few months.”

Muniain is a product of Bilbao’s youth system and has made over 200 appearances for the Basque club since being called up to the senior squad in 2009.

In other injury news, Bilbao have also lost the services of midfielder Ander Iturraspe for several weeks, after the player tore a muscle in his right leg.