By ESPNSTAR.com staff
Barca had been leading Saturday's La Liga match at the Benito Villamarin through Sergio Busquets' opener, and looked to be coasting towards victory.
However, Alves received his marching orders early on in the second half for a lunging tackle on Jefferson Montero, allowing Betis back in the game where they then went 2-1 up thanks to a Ruben Castro brace.
Seydou Keita saved his side's blushes by netting an equaliser late on but despite Alves almost costing them victory, Guardiola believes the Brazilian is indispensable.
"In the first half, we played very well," the former Spain international remarked about the match.
"However, we lost control at the start of the second half and after Alves' sending-off it was a different game.
"Alves exit rumours? It's not up to me anymore, but for me he is irreplaceable."
Guardiola also quashed suggestions the league would be lesser without his presence by the Nou Camp touchline.
"La Liga existed before me and will exist after me," he added.
Guardiola leaves the Catalan side having led them to three La Liga crowns, one Copa del Rey and two Champions League titles.