A dream debut for Dani Olmo in Barcelona's win over Rayo Vallecano

Down 1-0 at the start of the second-half against Rayo Vallecano, Barcelona manager Hansi Flick decided to shake things up a bit and subbed on Dani Olmo.

The Catalan side's marquee signing, Olmo had been unable to feature in Barcelona's previous two matches as he was not registered in LaLiga.

Better late than never as the academy product completely changed the game once he entered the pitch.

The first half saw Barcelona take a long time to get into the game and that lack of intensity is why Rayo Vallecano went ahead. They were knocking on the door a handful of times before letting themselves in.

But Olmo's introduction changed Barcelona as he played the ball quicker, thus elevating Barcelona's attack in transition. That elevated tempo is what resulted in the equalizer.

Pedri, through the middle, laid the ball off to Raphinha. The Rayo defense seemed more preoccupied with Robert Lewandowski that they lost track of Pedri. The Brazilian passed to Pedri who had some trouble controlling it. He managed to do so and then placed the ball past the outstretched arm of the goalkeeper.

Barcelona found the equalizer and knew Rayo was there for the taking.

They thought they found a second once Lewandowski placed his shot to the far post. However, Jules Kounde would be called for a foul in the build-up after a VAR review. It was only one of a handful of decisions by referee Soto Grado that left Barcelona supporters fuming.

Ten minutes after Barcelona initially thought they took the lead, they finally did so thanks to their newest signing.

Lamine Yamal, who had been relatively quiet, linked up with his Spain teammate and fed him inside the box. Olmo took some time to set up his shot and bent it past the goalkeeper to culminate his Man of the Match performance.

"Since I arrived i have been looking forward to my debut," Olmo said. "We hadn't won here in years. I have felt very good on the pitch, physically as well. I will always try to give my best wherever the coach puts me."

Indeed, it's true. The win marks the first time Barcelona have won in Vallecas since the 2018-19 season under Ernesto Valverde.

However, it wasn't all good news as Marc Bernal suffered a knee injury in the final minutes of added time. He needed help getting off the pitch and signs point to an ACL injury which could mean the end of his season only three games in.

Flick has been dealt a difficult hand to start his tenure. But he's won his first three games, picked up nine points, and has Barcelona playing pretty good football despite missing a number of first team starters. He'll once again have to adapt when Barcelona take on Valladolid on Saturday.