Until that point, Barca had enjoyed the lion's share of possession, but it was Granada who had come closest to opening the scoring when Yan Eteki hit the post.
However, Barca always looked the more likely winners, and they took advantage of the gaps that opened up in the final 20 minutes after German Sanchez was sent off for the visitors.
Despite scoring only once, Barca supporters will be satisfied with the performance. They dominated the ball, rarely went aimlessly long and pressed diligently when they gave possession away.
There was also an encouraging cameo from B-team midfielder Puig, who was making his first appearance of the season. Many have wanted him more involved for a long time, and you could see why. He won the ball back to help set up the only goal of the game and created another good chance for Griezmann, who could only find the side netting.
While the display was good, Setien still has plenty of work to do. For all the possession they had, they didn't create enough clear-cut chances before Messi's goal. They also, once again, leaned on Messi in the second half as they sought a winner.
Manager rating out of 10
6 -- You can already see what Setien wants. He has not come in to improve results, necessarily, but to improve the way the team plays. To do that, he shifted to a back three with the ball, allowing Jordi Alba to push on. He also picked Samuel Umtiti over Clement Lenglet, an early indicator that he's going to lean to players more prepared to take risks with the ball.
Player ratings (1-10; 10 = best. Players introduced after 70 minutes get no rating)
GK Marc-Andre ter Stegen, 6 -- Barca had north of 80% possession, and, aside from Eteki's shot of the woodwork, he had very little to do on his return from a knee problem.
DF Sergi Roberto, 6 -- Handed a new role by the new manager. The midfielder-turned-right-back was asked to drop in alongside Pique and Umtiti to form a back three here. Did well, but it meant his attacking output was limited.
DF Gerard Pique, 6 -- Untested by a Granada side who were pinned back in their own half.
DF Samuel Umtiti, 7 -- Like his teammates, he had little to do defensively, but where he differs is his ability on the ball. His passing between the lines could be a huge asset under Setien.
DF Jordi Alba, 7 -- In contrast to Sergi Roberto, his attacking output was maximised. Setien asked him to play as a left-winger when Barca had the ball, and he created a number of chances.
MF Sergio Busquets, 8 -- May prove one of the biggest benefactors of Setien's appointment. He has admired the coach from afar previously and produced one of his better performances this season in his first game working under him.
MF Arturo Vidal, 7 -- A controlled performance from the veteran, who was involved in some of Barca's best attacks, winning the ball back high and linking well with Messi. Set up the goal with a great piece of skill.
MF Ivan Rakitic, 5 -- His position in the side will be under threat when Frenkie de Jong returns from suspension, especially now that Arthur is fit again, too. Was the weak link in midfield at times, giving the ball away and once even getting in Messi's way.
FW Ansu Fati, 5 -- Handed his chance with Luis Suarez and Ousmane Dembele injured and found himself in some great positions. However, Barca will look for him to be more efficient with the ball moving forward, in both crossing and shooting positions.
FW Lionel Messi, 8 -- Barca's biggest threat once again and took his goal really well, his 14th of the season. Had earlier come close with a couple of free kicks.
FW Antoine Griezmann, 6 -- Worked really hard in a role with more freedom than when under Ernesto Valverde, but he missed his best chance, which came his way late in the second half.
MF Riqui Puig, 7 -- Came on and had almost an immediate impact, helping create the goal. There will be calls for him to be more involved now.
FW Carles Perez, N/R -- Replaced Ansu too late to really contribute.
MF Arthur, N/R -- Came on too late to do anything, but Barca will be boosted by his return. This was his first outing since Dec. 1.