The Hansi Flick era kicked off on the right foot as Robert Lewandowski scored two second half goals to deliver Barcelona a 2-1 win over Valencia.
With the number of players missing, Flick put out a bit of a makeshift starting XI with Marc Casadó and Marc Bernal as the double pivot. Ferran Torres, Raphinha and Lamine Yamal started behind Robert Lewandowski.
Despite a decent opening five minutes or so, Barcelona failed to threaten the Valencia goal. The only dangerous effort came from Raphinha with a strong shot from outside the box that was easily stopped by Giorgi Mamardashvili.
Valencia looked the dangerous of the two and finally broke the deadlock in the 44th minute as Hugo Duro connected on a cross and headed past Marc-Andre ter Stegen. The goal was initially called off due to offside but was later given as Iñigo Martínez played Duro onside.
Given how feeble the attack looked throughout the first half, it appeared like it was going to be a hard task for Barcelona to get back in the game.
But it wouldn't take long for the Catalan side to equalize.
In the final minute of added time, Alejandro Balde sent in a cross to the back post, which found Lamine Yamal. The 17-year-old then struck it back across the goal to Lewandowski who stuck his foot out with a defender almost on top of him.
It was a much needed goal to shift the momentum and go into the break tied.
Barcelona finally switched on coming out of the break. Yamal had a great opportunity to give Barcelona the lead but his shot was weak and into the hands of Mamardashvili.
In the 49th minute, a hopeful ball destined for Raphinha looked to be well short. The Brazilian, however, got in front of the defender who ended up catching Raphinha and Barcelona was awarded a penalty.
Lewandowski stepped up to take it and, without the skip, converted a near perfect penalty to give Barcelona the lead.
Barcelona had a couple more opportunities to increase their lead but wasted those chances. Ferran Torres missed a one-on-one before he was subbed off and Casadó had a golden opportunity to put the game to bed late only to see his shot go wide.
Unlike last season, this time Barcelona were able to hang on and did a rather good job in limiting Valencia's chances once they went up in the scoreboard. The Catalan side passed the ball around well and pressed Valencia late in the game, showing at least early on an improvement in their fitness late in the game.
Flick won't have been happy to see his team's display in the first half. However, Barcelona were much better in the second half, in particular once Pedri entered the game.
"In the first half we had problems getting to the goal, and in the second half we were much better," Lewandowski said. "It is very important to start the league with a win, and even more so at Mestalla, which is a difficult ground."
Barcelona won their first game of the season for the first time in two years. The last two openers, they were held to scoreless draws against Rayo Vallecano and Getafe.
The Hansi Flick era thus begins with a win and with a lot of room for improvement. Fortunately for Flick and Barcelona, they should get a couple of their players back in time for their next game, which will be an interesting one considering the rumors, against Athletic Bilbao.