The 17-year-old Barca youth product latched onto a pass on the edge of the box and beat goalkeeper Unai Simon with a low shot after only his second touch of the ball to score his first league goal quicker than any player in the club’s history.
Barca climbed one place with 24 points to close on Real Madrid, who were held to a 1-1 draw at Sevilla on Saturday.
‘We knew they (Bilbao) were going to put constant pressure on us,’ said Xavi. ‘They have done an extraordinary job.
‘It has been difficult for us (but) if anyone deserved the victory, it was Barcelona.’
Marc Guiu scored the winner 33 seconds into his Bacelona debut on Sunday
The forward coolly slotted the ball past the Bilbao keeper Unai Simon in the 80th minute
Barca, without the injured Frenkie de Jong, Pedri and Robert Lewandowski, had more possession but created fewer chances than the visitors in the first half, where their best opportunity saw Joao Felix hit the bar after 10 minutes.
Bilbao could have taken the lead when Inaki Williams’ effort was saved by Marc-Andre ter Stegen before the goalkeeper then denied Nico Williams in first-half stoppage time.
The visitors had lost left back Yuri Berchiche midway through the first half as he appeared to hurt his ankle.
Barca were sharper in attack after the break but their Spain keeper Simon kept out Felix twice and held firm until striker Guiu scored in the 80th, seconds after replacing Fermin Lopez.
At 17 years 291 days, Guiu became the youngest player to score for Barcelona on his debut in LaLiga this century.
Barcelona forward Joao Felix takes on Athletic Bilbao’s Benat Prados on Sunday
‘I can’t believe it. I’m out of breath, enjoying the moment,’ he told Esports 3.
‘This is unimaginable. I’ve been working all my life to take advantage of opportunities and it’s come to me.
‘Joao Felix controlled the ball, I saw that there was space behind the defence, he gave it to me and I beat Unai Simon. It’s an honour to have scored a goal against a goalkeeper of his calibre’.
Barca host Shakhtar Donetsk in the Champions League on Wednesday before hosting Real Madrid next Saturday.
