The greatest team ever?
Football first. Arsenal's is a feat without precedence in the modern game. Preston managed to go unbeaten in 1888, but that was in a 22-game season, in an era when football was a very different sport.
Nottingham Forest went 42 matches unbeaten from November 1977 to December 1978 - but that was across two seasons. Overseas, Steaua Bucharest went unbeaten from the start of the 1986-87 season to September 1989, a total of 104 matches.