And Coutinho grabbed his chance with both hands in Wednesday's second leg, scoring twice as Barca heaped more Copa del Rey misery on Sevilla, whom they battered 5-0 in last year's final.
"We want him to be happy and that's it".
It was the first penalty Barca had conceded all season, the first time Banega had failed from the spot after 13 attempts and the first penalty the Barca keeper had ever saved.
He sent another shot just wide, while Sergio Roberto clipped the ball over the bar as Barca tried to kill the tie off, but it was not until the 89th minute that Suarez was on hand to finish a counter-attack led by Messi and aided by Jordi Alba to assure Barca's qualification.More news: Manchester United vs Burnley
Ivan Rakitic then turned in a perfectly-weighted long pass by Arthur for Barcelona's second goal in the 31st.
Guilherme Arana pulled one back for Sevilla, but fine team goals from Luis Suarez and Lionel Messi sealed the win.
The 26-year-old Brazil worldwide has also thanked the Argentine ace for letting him take the penalty.
Coutinho arrived a year ago to Camp Nou after Barcelona paid Liverpool a club record fee of 160 million euros (then $192 million). Earlier Real Betis, whose Benito Villamarin stadium will host the final in May, beat Espanyol 3-1 at home after extra-time to progress 4-1 on aggregate.
Espanyol was leading thanks to Leo Bapistao's headed goal until Giovani Lo Celso levelled in the 76th.