Teenage debutant Marc Guiu said he will not be able to sleep after snatching champions Barcelona a 1-0 win over Athletic Bilbao just seconds after coming on from the bench on Sunday in La Liga, taking the Catalans up to third.

Xavi Hernandez's Barca will face leaders Real Madrid next Saturday in the Clasico just one point behind their bitter rivals, and second-placed Girona, who beat Almeria 5-2 earlier on.

For a long time it seemed like Barcelona would not find the breakthrough against their Basque visitors but striker Guiu, 17, netted under a minute after being thrown on by Xavi.

The forward was slipped in by the silky Joao Felix and slotted past Unai Simon, who got a hand to his shot but could not keep it out.

"Tonight I won't sleep," Guiu told DAZN.

"I can't believe it, I can barely breathe, I'm enjoying the moment."

Guiu became the latest on a conveyor belt of youths to make their debuts for Barca as their La Masia academy continues to produce gems.

"It surprises me that they aren't scared, I see them with a spark, they look at me with a face saying 'Put me on, you'll see that it will go well'," said Xavi.

"I saw that with Gavi, Balde, Lamine, Fermin, and with Marc, he doesn't look afraid."

Xavi started Inigo Martinez at the back against his former club and 20-year-old Fermin Lopez on the left of the attack, another academy product, with Barcelona down to the bare bones.

Several regular starters, including key striker Robert Lewandowski, are out injured.

Felix clipped the top of the crossbar but the hosts were negated in the first half by former Barcelona coach Ernesto Valverde's Athletic, who took the sting out of the game and occasionally sprang forward with both Williams brothers threatening from the flanks.

Marc-Andre ter Stegen tipped over an Inaki Williams effort and then parried a strike from the Ghana international, with Martinez producing a sublime block to deny his sibling Nico from the rebound.

Approaching the hour mark Barcelona carved out their best chance, when Simon brilliantly denied Lopez from close range, after initially saving from Felix's low strike.

Another followed when Felix fed substitute Lamine Yamal in the area but the 16-year-old starlet dragged his shot wide of the near post.

The teenager's arrival helped Barcelona gain the upper hand and Joao Cancelo was the next to draw a save from the watchful Simon.

- Instant impact -

Xavi brought on Guiu in the 79th minute and with his very first touch he broke into the area and then with another confidently fired past Simon.

"It's the best day of his life, surely," added Xavi.

Full of energy, the striker was soon booked for an attempted slide tackle which caught the goalkeeper as he tried to stop him clearing his lines, as he was roared on by the jubilant home fans.

"Today we scratched back two points on Madrid and it's vital to win this Clasico because we're playing at home," added Xavi.

Barcelona's victory takes them above Atletico Madrid, fourth, while Valverde's Athletic are sixth.

"I'm annoyed because it went just past me and maybe I could have done a bit more," Simon told DAZN.

"We really wanted to get three points to make a big gap above seventh place."

Earlier Girona thumped bottom-of-the-table Almeria after coming back from two goals down.

The Catalan side continued their superb season, levelling leaders Real Madrid on 25 points after 10 games after Los Blancos drew 1-1 at Sevilla on Saturday.

Almeria, still chasing their first win of the season, moved ahead when Leo Baptistao netted after two minutes and then struck again mid-way through the first half to delight coach Gaizka Garitano in his first game.

However Michel's Girona responded in a remarkable six-minute salvo before the break, started by Ivan Martin in the 37th minute after he had an earlier strike ruled offside.

Artem Dovbyk bagged a brace of his own with two neat finishes in the 39th and 43rd minute to send the hosts ahead.

Brazilian winger Savinho and substitute Cristhian Stuani rounded off the rout.

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