Arsenal could be without a natural left-back to start the Premier League season, with Unai Emery saying Nacho Monreal is doubtful because of a knee problem.
That could leave midfielder Ainsley Maitland-Niles as Unai Emery's only option in the left-back position against Manchester City next weekend, although the Spaniard insisted he has "great" confidence in the 20-year-old.
Monreal returned for preseason training this week following his World Cup break but has yet to train with the rest of the team, Emery said.
"He arrived with no big injuries, but his knee has a little problem," Emery said. "He's training every day but not with the [team]. He's doing the work alone with a physio, and running. We think maybe on Tuesday he can start with the team."
Emery admitted it will be "difficult" for Monreal to be ready for Man City but said he has no qualms about using Maitland-Niles at left-back, where he played against Lazio.
"My confidence in all the players is great. If he's OK to play, Nacho, that's perfect. But if he's not OK we can also have this chance with Ainsley," Emery said.
The Arsenal boss handed debuts to new signings Lucas Torreira and Stephan Lichtsteiner, with both playing the first 60 minutes before being taken off. Those two also only have a week of preseason training and Emery said neither is fully match fit -- but wouldn't rule out using them in the season opener.
"It's clear in the first week working they aren't in the best moment physically," he said. "But we want to continue working with them and also looking if they are OK physically and with the performance, and [if they are] better also than another player who was working with us, to choose the player for the first XI."
Emery still refused to divulge who his starting goalkeeper will be to start the season, with Bernd Leno playing the full game against Lazio after Petr Cech was in goal against Chelsea. He also brushed aside a question about whether he expects to sign another player in the final week of the transfer window, but admitted the club is likely to trim the squad.
"My focus is very concentrated on the first match and preparing, and not the window and the possibility to sign another player," he said. "Maybe we need to [sell] some player, because we are more than [we need in] the squad."