I think an underatted team was Ac Milan from 2003-2007, they had a lot of talented players. They had such a great defense and offense. They had superstars all over with guys like Pirlo, Gattuso, Nesta, Cafu, Dida, Kaka, Shev,Crespo. Spain struggled against Italy a few times (2008 and 2012) which shows that Italian football style would have been an issue for Barcelona if they faced them more often.
Honestly no one .
2008 Numancia, 2008 Wisła Kraków, 2008 Shakhtar Donetsk, 2009 Espanyol, 2009 Atletico, 2009 Mallorca, 2009 Osasuna, 2010 Atletico, 2010 Sevilla, 2010 Inter, 2010 Hercules, 2011 Real Sociedad, 2011 Real Betis, 2011 Real Madrid,…
Bayern 2020. The most dominant team in football history by far
Pep’s Manchester City (2022-2023) – they were absolutely insane and they won the Treble.