I think the importance of today's Brentford game is high. If Arsenal can win this match, the difference in points will increase. According to the result of the match with Manchester City, it will now be easier to talk about who will be the champion in this league. I don't think there's any reason why Arsenal shouldn't be champions 
It's a big surprise for everyone when Arsenal lose points in league games. But the same is not true for Manchester City, in my opinion. Of course, the league is a long adventure. Arsenal may lose a few more games. But I get the impression that Manchester City will lose more games this season. Therefore, Arsenal are closer to the championship, even if they lose to Manchester City. I think winning this match will not be decisive in the league championship. Of course it will be an important match. But the league is a long adventure. And Arsenal have a more dynamic team image.