Isco and his team-mates landed in Abu Dhabi on Monday to defend their Club World Cup title, although the midfielder may have a bit-part role in the tournament.
"We all know his quality. For me it's him who has the most ability and quality on the pitch," Marcelo told a news conference there on Tuesday.
"A lot of meaning is being given to something that isn't that important, some play more at times and others play less. As players we have our moments.
"We don't have to talk about it much more. He's at Real Madrid until the death like all the players."
Solari said that Isco is working hard ahead of Wednesday's semi-final clash with Japanese side Kashima Antlers.
"We are focusing on the game against Kashima so I see (Isco) and everyone else working with the enthusiasm that this game deserves, that they earned (by winning the Champions League)," said Solari.
(Reporting by Rik Sharma; Editing by Hugh Lawson)
