冷门 (冷門) lěngmén

lěngmén noun a neglected branch (of arts, science, sports etc); a complete unknown who wins a competition
Domain: Modern Chinese 现代汉语
Notes: (CC-CEDICT '冷門')

Contained in

• 爆冷门(爆冷門) an upset (especially in sports); unexpected turn of events; to pull off a coup; a breakthrough
• 爆冷门儿(爆冷門兒) an upset