Arsenal boss Mikel Arteta has explained Thomas Partey was not ready to start against Manchester City.
The midfielder joined on deadline day in a £45million move from Atletico Madrid to bolster Arteta's side.
But while he started on the bench at the Etihad, Scotland defender Kieran Tierney was cleared to play despite having to quarantine after his international teammate Stuart Armstrong tested positive for Covid-19.
On Partey, Arteta told Sky Sports: "We were tempted but he had a day and a half of training, a lot of new things establishing here but we need to be a little patient and respect some timings."
And on Tierney, he added: "The doc and the club dealt with [Tierney], we had permission from the Premier League and that's all."
Arsenal beat City in last season's FA Cup semi-final and Arteta hopes for a repeat performance tonight.
He said: "We had the previous two games that we played against them [in mind] and obviously everything they've been doing since the start of the season. It's an accumulation of a lot of different factors."
Meanwhile, former Gunner Sol Campbell backed Arteta to succeed at his former club.
"He's had a great time at Manchester City, he's learnt a lot, for sure, but the main thing is he's taken it on," he added.
"He's got the young players playing, he's got everyone at the club buzzing again.
"The players want to get into the team, and if you fall out of line, you're out and some players have suffered that.
"But the main thing for me is he's got everyone playing, everyone is working hard and playing for the shirt.
"There's no-one slacking off any more and young players have stepped in and done really, really well.
"I'm happy for him because he's done it in super quick time but not getting carried away.
"Every time they're going out, playing well. They're playing a good team today but we're a good team as well and in fantastic form.
"It's apparent all the fans are really really happy and it's all about staying in the top four now."
