Barcelona may have to do without Sergio Busquets and Arda Turan in the second leg of their Copa del Rey quarter-final with Athletic Bilbao after the duo missed Monday's training session due to illness.

Busquets and Turan both started Saturday's 2-1 La Liga victory at Malaga, but are doubtful for Wednesday's clash at Camp Nou.

Barca won last week's first leg 2-1 at San Mames as they continue their quest to retain the Copa, which they won last season by beating Bilbao in the final.