William Saliba
This has to be the toughest test Saliba has endured all season. The Frenchman has snuffed out the threat of many a centre forward since August, but today he was given a pretty torrid time by Ivan Toney. Saliba's physicality and dominance in the air has been such a strength this season, but that counted for little against Toney, who won almost everything that was played up to him and consistently overpowered the Arsenal centre-backs, Saliba especially. To his credit, Saliba battled until the last minute, but he will certainly have been happy to hear the full-time whistle.
Gabriel Martinelli
It's just not happening for the Brazilian at the moment. Many wondered whether Arteta would leave him out against Brentford in favour of Leandro Trossard, but the Arsenal boss stuck with the winger despite his recent under-par performances. Unfortunately for Martinelli, he couldn't repay that faith and it was no surprise to see him replaced just after the hour mark. He's been electric for Arsenal this season, but there has undoubtedly been a drop off in recent weeks. He's yet to score this year and never looked like breaking that barren run against Brentford's well-disciplined defence.
Arsenal's momentum
It's three games without a win now for Arsenal in all competitions. It's far too early to call it a crisis just yet, but there's no doubt that their confidence has taken a hit over the past fortnight. The energy and intensity that they've shown all season has been lacking in recent games and that will be a worry, with Manchester City to come on Wednesday night. Mikel Arteta's side built up so much momentum during the first half of the season and they were clearly feeding off that. That has been halted now and questions are being asked of them, how they respond over the next few games will be key to their title hopes.