Mikel Arteta did not hide his frustration with Arsenal's performance in Thursday's 2-2 draw with Sporting CP, but Fabio Vieira's display brought him a degree of pleasure.
The Gunners took the lead in the first half when William Saliba headed in from Vieira's corner, only for their hosts to level in similar circumstances just past the half-hour mark at the Jose Alvalade.
Paulinho put Sporting in front after the break with a tap-in, but Hidemasa Morita's own goal seven minutes later ultimately secured Arsenal a draw to take back to Emirates Stadium for the return leg of their Europa League last-16 tie.
The draw puts Arsenal – who have only lost at home twice all season – in a decent position ahead of the second leg, but Arteta feels they can do better, even considering the somewhat unfamiliar look to his starting XI.
"We are conceding too many simple goals," he told reporters.
"We spoke about the importance of boxes, especially in a competition where you're in or out. [On Thursday], we didn't defend that well enough, and we have to be better at threatening the opponents as well.
"But of course, you have an opponent there. We've played some really emotional games recently.
"We made a lot of changes and sometimes that takes time to get that cohesion, and you could feel it in the first 15 minutes that it needed some time to adapt and click.
"If we don't expose them, though, that's never going to happen."
He added: "When you concede two poor goals like we did away from home in Europe, it's very difficult to get a positive result.
"The game had different phases because we gave too many simple balls away in our own half and gave them the capacity to [exploit] transition moments, which they are good at.
"In other moments we had total control of the game and we lost a little bit of threat, especially with the four players we are missing in our frontline.
"There were some positives because we showed a lot of resilience to get back into the game, but we need to defend our box much better and be better on Sunday."
Vieira's performance was a surely one of those positives.
The Portugal international was given only his 13th start of the season, but his delivery for Saliba's opener was his sixth assist already – only Bukayo Saka (nine) has more for the Gunners this term, and he has played almost 1,600 minutes more than Vieira.
Arteta clearly values the former Porto midfielder.
"I'm really happy with him," he added. "I think he deserves more minutes than he's had, especially in the last two months.
"Obviously he had a difficult start because he was injured for two months after a surgery, and wasn't at the level that we want.
"You saw tonight he was probably our most dangerous player. He was always making things happen. He's a player that I absolutely love."