"It's a special thing to reach a final and I am sure it will be a great game, but also a hard one, like all finals are". Sevilla beat Leganes 2-0 on Wednesday to go through 3-1 on aggregate.
"For me it is my first final, so it is a very special moment", Coutinho told Spanish TV station Gol. 'I was looking for the goal in the first few games and today I got it and, most importantly, helped the team reach the final'.
Valencia had lost their last three matches in a row but looked the more risky in the first half, with Rodrigo Moreno powering their best chance off the underside of the crossbar.
Philippe Coutinho broke the deadlock five minutes into the second half, tucking home at the back post following a cross from Suarez, 0-1 and 0-2 on aggregate.
At 0-0, striker Rodrigo headed against the crossbar before Jasper Cillessen produced a stunning instinctive save to deny full-back Jose Luis Gaya from point-blank range following Coutinho's opener.
Messi hit an effort just wide, and the closing stages of the first half saw Suarez miscue a shot inside the box, allowing Domenech to gather, before Valencia's Geoffrey Kondogbia sent a shot into the side-netting having combined with Daniel Parejo.
Ivan Rakitic, also teed up by Suarez, then added the visitors' second in the 82nd minute to secure progress to a showdown against Sevilla in what will be defending champions Barcelona's fifth consecutive Copa del Rey final.
The only concern for Barca will be the sight of Pique in obvious discomfort after going off late on to be replaced by €11.8m man Yerry Mina, who made his debut.