Victory for Barca would only slightly alleviate the disappointment of failing in the Champions League but another defeat, less than three weeks after the collapse at Anfield, would plunge the club back into crisis, AFP reported.
For Valencia, the possibilities are more positive, given a loss in Seville is expected, while a win would turn a decent campaign into a sensational one.
The numbers favor Barcelona. Twenty-six points separate the two sides in the table, with Barca scoring more goals than Valencia has scored and let in put together.
Valencia's captain Dani Parejo finished club’s top scorer on nine goals, the same number Lionel Messi had hit before the middle of November.
And Valencia has beaten Barcelona only once in 14 attempts, without a success in any of their last eight meetings.
But the records ignore trajectory and momentum. Barca looks like a side still hurting, eager to end the season and begin recovering over the summer. Valencia is flying high, fresh from a late surge that saw it snatch fourth place last Saturday.
After beating Real Valladolid, Valencia's players celebrated like they had won a trophy.
"It wasn't easy to turn it around," said coach Marcelino.
"But we did it."
A day later, Barcelona ended with a 2-2 draw away at Eibar.
"We weren't playing for anything and it showed," said Ernesto Valverde.
"In Seville, we will be completely different."
Barcelona is depleted. Luis Suarez and Marc-Andre ter Stegen are out with knee injuries. Philippe Coutinho, Ousmane Dembele and Arthur Melo are all struggling. Nelson Semedo and Kevin Prince-Boateng might not have started, but they are unlikely to make it either.
When the club's president Josep Maria Bartomeu was asked for his reaction to winning La Liga last month, with three games to spare, he said, "We want to win the treble".
The idea was the Copa del Rey would be the easy part, a warmup for winning the Champions League final in Madrid seven days later.
"It was said we had given up in the Copa de Rey, that we didn't want it," Messi said after his team reached the semifinals.
"But in no way is this the case. This team wants to fight for all three titles as is the obligation of Barca every year."
Another domestic double, Valverde's second in as many years, would be celebrated on Saturday but still deemed a failure next week. Lose and even the league title might be almost forgotten.
Barcelona's consistency in Spain has reduced the impact of its success. The Catalans have won the title eight times in 11 years and this weekend can win the cup for a record fifth year in a row.
"The league is the one that shows who has been the best, the most consistent," said Sergi Roberto last weekend.
"We have had a magnificent season."
Valencia last won it 11 years ago, Fernando Morientes scoring in a 3-1 victory over Getafe in a stadium that no longer exists. That was the last trophy the club hoisted in any competition at all.
After 15 games this season, Valencia sat 15th in La Liga, a battle against relegation more likely than a late push for the top four.
"I can't explain it," said Marcelino, who was the club's 12th coach in five years but this time the club persevered and his team's form returned.
It made the Europa League semifinals, beaten by Arsenal, and then saw off Valladolid last week to reach next season's Champions League.
The result may not be remarkable – it made it last year too – but it was the way it did it. Unlike Barcelona, the adversity enhanced the achievement.
"It has been an outstanding season," said Marcelino.
"We have had a lot of problems but we stayed calm. To get back into the Champions League again is a great achievement."
The same parameters now frame this final, Barcelona aiming to meet expectations, Valencia hoping to exceed them.
"We have to go again," said Valverde.
"It's one goal done after a difficult season," said Valencia's Parejo. "There is still one more to do."