Arsenal boss Unai Emery had his players take part in a behind-closed-doors friendly against Crystal Palace the day after their Premier League defeat by Manchester City.
Summer signings Bernd Leno and Lucas Torreira both started in the fixture at the club's London Colney training ground, while Danny Welbeck and Emile Smith-Rowe also featured.
Arsenal won, with the scoreline believed to be 4-0, and the game was set up following a simple phone call between the clubs at Emery's request.
Insiders described it as an 'old-school' 11-a-side friendly with players wearing bibs and no-one other than the squads and coaching staff invited.
This is understood to be the third 'secret' fixture set up by Emery so far this season with Crawley Town having also faced the Gunners in London.
The Arsenal boss is keen to boost his players' fitness. The XI that started in their 2-0 loss to City were not made to take part.
Emery and Palace boss Roy Hodgson spoke afterwards and have agreed that, if both clubs find themselves in similar situations later this season, they will play again.