With Quique Sanchez Flores's men committing more men in attack, Barca were increasingly unsafe on the break and Lopez had to make a superb double save from Suarez and Ivan Rakitic after Messi had played Coutinho into space on the left.
Leo Messi has shown no signs that his career is ready to slow down as he played a key role for Barcelona as they progressed to the semifinals of the Copa del Rey on Wednesday with a 2-0 victory over Espanyol at home.
However, the hosts were not as clinical in the first half so Valverde sent on Paulinho and then gave Coutinho his Barcelona debut.
The Brazilian midfielder came on as a 68th minute substitute for Andres Iniesta - we'll let you process the symbolism there.
Messi's goal to put Barcelona 2-0 ahead in the game and in front in the tie was the club's 4,000th at the Nou Camp in official competitions since it was opened just over 60 years ago.
Messi and Suarez missed chances in quick succession, the latter set up by the lively Coutinho.
Titular de Sectur propone legalizar la marihuana en áreas turísticas
Afirmó que la legalización de la mariguana en el país "no tiene una explicación científica, es una explicación política y de falta de información ".
Fans of the the Catalan club were understandably delighted to see their new player for the first time and will be hoping that he can produce the kind of form that endeared him so wholeheartedly to the Liverpool faithful.
Have a look at the advice Coutinho got from recently retired Ronaldinho.
The Brazil worldwide admitted that he was nervous about making his first appearance, although he's thankful to the Barcelona fans for giving him a warm welcome.
"I was a bit nervous and anxious, but later I calmed down and adapted to the game". I was moved by my reception.
Coutinho added: "It's a special night and we've managed to win the game, which is the most important thing".
"We feel like we played a great tie".