Arsenal boss Mikel Arteta said Cristhian Mosquera is "fine" and was taken off as a precaution during Monday night's 1-0 win at Aston Villa after the Spanish defender reported feeling pain.
Arteta did not want to take any risks with the 22-year-old, replacing him in the latter stages with new signing Ezri Konsa, who was booed on his return to Villa Park.
"We knew that if we had an injury on the back line with Jurrien [Timber] out, we'd be in big trouble -- so we had to do Ezri," Arteta said after the match, in which Bukayo Saka's second-half goal made it two Premier League wins out of two for the champions.
"Mosquera could not continue, so we know the depth has to be really big when we're fighting for four competitions in the manner that we play as well.
"He's fine, but he was feeling like he was about to have something, and that's why we have the bench that we have, and that's why we had to bring Ezri in.
"Ezri makes a debut in really difficult circumstances; it's not easy emotionally to come here and play. But he looks so composed, so calm, so in control."
Riccardo Calafiori said the result was more important than the performance as the Gunners got the job done.
It was far from a vintage performance, scoring with their first shot on target just before the hour, but they ground out the win in familiar fashion.
"I'm so happy with the clean sheet, especially when I talk with the guys -- the defenders -- I always say that if we don't concede, we obviously have much more chance to win the game, and I think we always do so well," the full-back said.
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"At the end of the game, it's so important for us, especially at a tough place like this one, we just want to win when we come here and we did it.
"In pre-season we were upset, I think we conceded too much, but then as the season started, we have all the players back.
"We fight, and you see how we do mistakes sometimes, but how we track back with the runs, it's unbelievable, and each player, even the attackers, so I'm so happy."
Calafiori set up Saka's goal -- his second assist of the season.
"I'm just so happy to pass the ball to B [Saka]," the 24-year-old Italy international added.
"As I say, it was a tough, tough game, we need these kind of moments, you know, to change the game -- and we did it."
