Passage: Aston Villa's arch-rivals are Birmingham City, with games between the two clubs known as the Second City Derby. Historically though, West Bromwich Albion have arguably been Villa's greatest rivals, a view highlighted in a fan survey, conducted in 2003. The two teams contested three FA Cup finals in the late 19th century. Villa also enjoy less heated local rivalries with Wolverhampton Wanderers and Coventry City. Through the relegation of West Brom and Birmingham City, to the Football League Championship, in the 2005–06 season, at the start of 2006–07 Premiership season, Villa were the only Midlands club in that League. The nearest opposing team Villa faced during that season was Sheffield United, who played 62 miles (100 km) away in South Yorkshire. For the 2010–11 season, West Bromwich Albion were promoted and joined Aston Villa, Wolverhampton Wanderers, and Birmingham City in the Premier League. This marked the first time that the "West Midlands' Big Four" clubs have been in the Premier League at the same time, and the first time together in the top flight since the 1983–84 season. Birmingham were relegated at the end of the 2010–11 season, ending this period.

Question: Who were their rivals?
West Bromwich Albion