Title: Perfect season
Passage: Many association football teams have also had perfect seasons, however doing so in a season of 20 or more matches is very rare. Clubs to have achieved this include: Dresdner SC of Germany in 1942--43 (23 wins out of 23), Ferencvárosi of Hungary in 1931--32 (22), Sunrise Flacq United of Mauritius in 1995--96 (22), and Nacional of Uruguay in 1941 (20). Al-Ahly (of Egypt) hold the record of going a whole season being unbeaten, in all possible competitions they were involved in (46 matches in total played in: Egyptian Premier League, Egyptian Cup, Egyptian Super Cup and CAF Champions League between 2005 and 2006). The longest winning streak of any team over multiple seasons was Sparta Prague's run of at least 51 wins in a row, between 1920 and 1923.
Question: has any team won the champions league undefeated
Answer: yes