Yet again, Juan Antonio Pizzi's side need a famous turnaround to progress after a disheartening 2-0 first-leg loss to Sevilla at the Ramon Sanchez Pizjuan last week, but they will have to do it without their young striker.
The Spain youth international has well and truly put himself in the shop window this season. Stepping into the void of the departed Roberto Soldado, the 20-year-old has been at the heart of every great moment los Che have enjoyed.
When they came from behind to beat Barcelona at Camp Nou, it was Paco who scored the winner. When they thumped Betis 5-0, Paco was the star, netting two goals. When Basel came to Mestalla with a 3-0 lead to their names, Paco led the fightback with his treble to create Europa League history.
And though he has done his club proud this term, he may well be off in the summer, with Barcelona, Real Madrid and Atletico Madrid all linked with his signature.
Valencia have long had to sell their star assets to stay afloat, even when they regularly reached the latter stages of the Champions League. In addition to Soldado, David Villa, David Silva and Jordi Alba are among the players who have departed the club in recent years, leaving big holes to fill.
Last year, they missed out on Europe's top competition after a dramatic final day of the Liga season and that was a financial disaster for the club. This time out, they look unlikely even to collect the wooden spoon of the Europa League - not what they can afford as they look to upgrade to a new Mestalla.
So where could he go? Talk of a move to Real Madrid or Barcelona seems rather fanciful, given his lack of experience and the presence of experienced stars in his position, but Atleti would be an intriguing option if they are unable to hold onto Diego Costa for another season.
Valencia, however, will be eager to hold on to him. They allowed Soldado to leave as they had Paco waiting in the wings, ready to step into the Tottenham striker's shoes. They do not have the same luxury this year. His contract expires in 2016 and included a buyout clause of €18 million. They will be praying that no one decides to exercise it.
For the player himself, leaving Valencia would be hard. Having come through the ranks at the club, they invested in his future and resisted the urge to spend the Soldado money on a proven performer, instead trusting in his talents.
However, a player of his age needs to be playing top-level football and Valencia cannot do that in their current state. With Atletico firmly part of the top tier of Liga clubs and Basque duo Athletic Bilbao and Real Sociedad strengthening, there is no return to the Champions League in sight.
A move to a club on the up could help him move to the next level, but Valencia are likely to fight to keep their man, regardless of whether they can produce a stunning comeback against Sevilla without him.