Coutinho could make his LaLiga debut when leaders Barca host Deportivo Alaves Sunday.
Their sudden rise in form has come at the ideal time as they head into a repeat fixture of last season's Copa del Rey final, which Barcelona won 3-1.
The 25 year old is his side's top scorer with 11 goals in all competitions this season.
Coutinho has revealed he was feeling anxious ahead of his debut agaisnt Espanyol - where he spent a season on loan in 2012 - but says the welcome he received from the Camp Nou enabled him to relax. However, the referee waved the visitors' appeals away and Barca survived.
"I think the teams that are in the last four are there because they have really worked hard". Aleix Vidal created the chance and his cross from the right was headed in by Suarez at the far post.
DF Samuel Umtiti, 8 - Made his first start since tearing his hamstring on December 2 but looked as fresh as ever, getting to every 50/50 ball before his opponent and always staying in control in possession.
Espanyol: Pau Lopez 6, Marc Navarro 6, Mario Hermoso 6, Naldo 6, Aaron Caricol 6, David Lopez 6, Sergi Darder 6, Javi Fuego 6, Victor Sanchez 6, Esteban Granero 6, Gerard Moreno 7.
DF Jordi Alba, 5 - Had an usually quiet game and was unable to connect with Messi for once.
"Besides a couple of misplaced passes, he didn't put a foot wrong".
Luis Suarez is back amongst the goals too, scoring at least one goal in each of his last 8 La Liga games for the club.
"He's different to any player we've got".
The second half continued in a similar vein with Messi hitting a shot, which took another deflection and flew just wide.