Jose Gaya gave the visitors the lead with a stunning strike on the half volley, but Ansu Fati equalised superbly following a lay off from Memphis Depay. The Dutchman then scored a penalty after Fati was fouled by Gaya in the box. Philippe Coutinho added a late third before Sergio Aguero came on for his debut.
It's easy to see why Barcelona want to renew Ansu Fati with a one billion euros release clause. He was worth his weight in goals against Valencia with a dynamic display that drove the team to a 3-1 victory.
Former Barcelona president Josep Bartomeu admitted last week that the club rejected a 150m euros offer from a Premier League club for Fati in 2020. His current deal runs out next year and there is a difference of opinion between his agent Jorge Mendes and the club as to whether that includes an automatic renewal to 2024. He must stay. It was tough losing Lionel Messi towards the end of his career. Losing the 18-year-old at the start of his would be just as hard to take.
Things had started badly for Barcelona with Jose Gaya making the most of space granted him on the edge of the area to shoot from long range past Marc Andre ter Stegen on five minutes. But the response was swift and ruthless. Lionel Messi used to do it from the left. Ansu does it from the right.
Drifting in from that flank he played the ball off of Memphis Depay before bending a right-foot curling shot past Jasper Cillessen to equalise on 13 minutes. Gaya and Ansu were at the centre of things again five minutes before half time when Barcelona took the lead.
The Valencia full-back nicked the ball from the Barcelona forward as he was about to turn it past Cillessen from the edge of the six-yard box from Sergio Roberto's cross. But with his follow through Gaya brought Fati down and that was enough to persuade referee Jesus Gil to point to the spot. With no run-up Memphis rifled the penalty high into the top corner to make it 2-1.