Holders Barcelona secured a place in the Copa del Rey final for the fifth season running, becoming the first side to achieve such a feat.
Coutinho, dressed in a black shirt dotted with white stars, was in the stands at the Camp Nou for the first time since his 160 million-euro ($192 million) move from Liverpool.
Coutinho signed a five-year contract to end a long-running transfer saga on Monday with Mestre revealing that Liverpool had originally asked for 200 million euros.
Barcelona are still unbeaten in La Liga this season and on Monday will officially unveil Coutinho following the Brazilian's 160 million-euro ($192 million) move from Liverpool.
Philippe Coutinhos move to Barcelona from Liverpool for a staggering 160 million Euros has helped him spiral as the second most expensive transfer in the world.
Philippe Coutinho finally got his wish on Saturday when Barcelona agreed to sign the Brazilian star from Liverpool for 160 million euros ($192 million) in the third richest deal of all time.
According to reports in Spanish media, Barcelona and Liverpool have agreed a deal in principle worth up to 160 million euros for Philippe Coutinho to move to the La Liga giants this month.
Brazilian international forward Coutinho has been linked with a 150 million euro (£134 million; $180 million) switch to the Spanish giants.
Liverpool playmaker Philippe Coutinho has refused to commit his future to the Premier League club Liverpool.
Liverpool are beginning to develop impressive momentum and have now collected 16 points from their last six league games.
Liverpool face Sevilla at the Sanchez Pizjuan on Tuesday knowing a win will secure their place in the last 16 of the UEFA Champions League.
A win will take Spurs or Madrid to the knockout stage.
Philippe Coutinho is set to start his first Liverpool game since trying to engineer a move to Barcelona when the Reds take on Burnley on Saturday, according to his coach Jurgen Klopp.
Philippe Coutinho has not yet played for Liverpool this season, with the club citing a back injury.
A leading Barcelona board member claimed Liverpool set an asking price of 200 million euros ($238 million) for midfielder Philippe Coutinho.
The transfer window shuts in England at 11pm BST on Thursday, August 31.
The Catalans have until Friday when the Spanish transfer window closes to agree a deal for Coutinho, who hasn't played for Liverpool since submitting a transfer request to try and force through a move earlier this month.
Barcelona believe the Brazilian international has the ability to not only replace Neymar alongside Lionel Messi and Luis Suarez in a star front three, but could also provide cover for 33-year-old captain Andres Iniesta in midfield.