The Welshman ran half the length of the field to score the winner five minutes from time and subject Barcelona a third consecutive defeat in all competitions which leaves them on the verge of failing to win a major trophy for the first time in six years.
“When you look at the age of the players in this team it is evident that Barcelona has a long road still to run and with a lot better results than this year,” said Martino.
Barcelona were dumped out of the UEFA Champions League before the semi-final stage for the first time in seven years last week by Atletico Madrid and also lie in third-place, four points adrift of Atletico, with just five games remaining in La Liga.
“Obviously it is not a happy moment,” Martino admitted.
“It has been a very hard week for us, but there is nothing else we can do but look ahead to what remains in the league. It is a very hard blow to take because the expectations for today were huge and it is a final so everyone was desperate to win.
“I am hurting due to the defeat and for the people that came here with great expectations to support us, but Barcelona still has a lot left to give. There is no perfect recipe to recover. The league doesn’t have a favourable look for us at the moment, but we have the obligation to fight until the last day.”
Defeat is also certain to heighten speculation that Martino will be replaced at the end of the campaign after just one season in charge of the Catalan giants.
However, the Argentine claimed the past week did not change his plans for the future.
“I don’t feel like my future changes because of what we have lost, nor would it have changed if we had won everything.”