Nikolay Lalov spent his entire competitive water polo career at Lokomotiv in Sofia before becoming one of the best referees in the sport in Bulgaria. As a youth player Lalov won several state championships in addition to representing the national youth team. He quickly went on to be an official in the sport and spent almost 45 years working as a national and international judge. Lalov judged matches at the European Championships, World Championships, Asian Games, and 1992 Barcelona Olympics. For recognition of his work FINA named him in their list of the best ten water polo referees of the 20th century.