Athletic Club "B", commonly known as Bilbao Athletic, is the reserve team of Athletic Club, a football club based in Bilbao, in the autonomous community of Basque Country in Spain. The team are playing in the Segunda Federación – Group 2. Founded in 1964, the team holds home matches at the small stadium attached to the club's training facility at Lezama, holding 3,250 spectators or occasionally at San Mamés Stadium, with its 53,500-seat capacity, for important fixtures.

San Mamés is an all-seater football stadium in Rafael Moreno Pitxitxi Kalea, Bilbao, Basque Country, Spain. Inaugurated on 16 September 2013, the stadium replaced the "old" San Mamés as the home of Athletic Bilbao. With a capacity of 53,331 seats, San Mamés is the 7th-largest stadium in Spain and the largest in the Basque Country.