Barcelona's latest homegrown hero, Marc Guiu, said he is "still flying" after scoring the winning goal against Athletic Bilbao 23 seconds into his debut on Sunday. With the game goalless at Barca's Estadi Olimpic Lluís Companys, Guiu was sent on for Fermin Lopez with 10 minutes remaining. Less than 30 seconds later, Joao Felix's pass sent him through on goal and the teenager finished past Bilbao goalkeeper Unai Simon to seal the victory. At just 17 years and 291 days, Guiu became the youngest debutant ever to score for Barca. The 1-0 win maintained Barcelona's unbeaten start to the season and moved Xavi's side to within one point of leaders Real Madrid and second-placed Girona. "I can't breathe. I'm just enjoying the moment, I'm still flying," said Guiu, who has come through the Barcelona system, starting at the Under-8s. "I have been working hard all season to take any chances should they come. When I saw the goalkeeper coming off his line, I decided to shoot. "Before going on, Xavi told me to just do the same as I do in the youth team. And to take any chances that came my way." Xavi, one of the greatest and most successful products of Barca's famed La Masia academy, has never been afraid of promoting the club's youth talent since returning to the club as manager in 2021. The likes of Gavi, Pedri, Alejandro Balde, and more recently Lamine Yamal, all have prominent roles in the first-team squad. The Barcelona manager is clearly a fan of Guiu, saying his starring cameo provided further proof of the youth talent available within the club. "He can score goals, he has spark. He's a player I personally like a lot," Xavi said. "I have no qualms about using homegrown players because we have loads of talent here. They put the same kind of trust in me in my day." Barca are next in action on Wednesday when they aim to make it three wins from three games in Champions League Group H. They face Ukrainian side Shakhtar Donetsk in Barcelona.