Memories of the 5-4 thriller at Ciutat de Valencia last season that cost Ernesto Valverde's men an unbeaten LaLiga campaign came flooding back during an end-to-end first half in which Levante thrived.
Levante did have their second in the 18th minute, however, when Boateng's clever pass found Borja Mayoral and the on-loan Real Madrid forward managed to squeeze his low effort through Murillo's legs and into the back of the net.
It took time for the away side's defence to find their feet and Levante had a brilliant chance to double their lead in the seventh minute when Emmanuel Boateng drove into the penalty box before looking to pick out the bottom corner, but Cillessen was down to make a smart save.
Arsenal target Denis Suarez was brought on however and won his side's penalty with six minutes remaining after a superb individual run down the inside right channel.More news: Announcement of India's probable squad for the first ODI delayed
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"Coutinho is a great player who has given us a lot and will give us a lot".
What does it mean?
That is, of course, unless the Blaugrana boss decides a fifth successive Copa del Rey triumph is not among the club's pressing priorities.
And debutant Murillo is hoping Barca, without Lionel Messi and Luis Suarez on the night, can build on Coutinho's strike in the second leg.
"But he (Coutinho) is a player which we consider as a starter and will be very important for us in the remainder of the season, for sure", he said.
Colombia worldwide Murillo has voiced a desire to turn his short-term stay into a permanent deal - which Barca can push through for €25million - but his first 90 minutes in the shirt did not do much to advance that cause.