Arsenal missed the opportunity to move eight points clear at the top as Ivan Toney headed in a deserved equaliser for Brentford to earn a 1-1 draw at the Emirates
The Gunners had been on course to bounce back from defeat at Everton and move well clear of their title rivals Manchester City, who can reduce the gap against Aston Villa live on  before playing Arsenal on Wednesday, when Leandro Trossard tapped home just five minutes after coming on as a second-half substitute
Brentford had seen Rico Henry miss a golden early opportunity before Toney hit the crossbar in an impressive first-half performance which should have had them ahead at the break
However, Thomas Frank's spirited Bees eventually found the net, hitting back through their talisman Toney, who controversially nodded in from close range to take a well-earned point, extending their unbeaten run in the Premier League to 10 games, and leaving Arsenal to settle for a six-point advantage over City
Mikel Arteta believed the equaliser should have been ruled out due to Ethan Pinnock standing in an offside position while blocking Gabriel as the ball was delivered into the area from a free-kick
"I just looked at it back and it is offside," he said
 "We'll probably be given an explanation later in the week but today we haven't got any
"Looking at the images, you have to apply certain principles in defending and you do that by sticking to the rules and suddenly you apply different rules then you have to change your principles
 So tell us before because then you don't hold the line that high because you're always going to have an advantage if you get blocked
"It's too late, the goal was allowed, we dropped two points
"Brentford should have led in the fifth minute when Toney was released in behind Oleksandr Zinchenko and delivered a low cross to the arriving Henry, who side-footed wide when it looked easier to score
Arsenal had another let-off just six minutes later as Bryan Mbeumo had the ball in the net, but play had already been brought to a halt - contentiously - after Toney rose to flick on a long pass
Brentford defended superbly, let down only by their composure in the final third during the first half as Toney missed a gilt-edged chance, side-footing against the crossbar from Mbeumo's pull back
Toney also saw a swerving long-range effort pushed away by Aaron Ramsdale while Ben Mee's goalbound header at a corner was blocked yards from the line
Arsenal needed to be more patient with their attacks and late in the half Martinelli volleyed narrowly over from inside the area after Gabriel's cross had been headed down by Granit Xhaka
They improved in the second half, playing with more purpose and intensity, eventually seeing Saka's low cross turned in at the back post by Trossard for his first Arsenal goal
Yet Brentford continued to believe they could force an equaliser and it only took nine minutes for them to respond
 Toney volleyed a free-kick back across goal, sparking head tennis in the box before Christian Norgaard turned it into the six-yard box for the striker to head home
 The VAR Lee Mason conducted a long check for offside before awarding the goal
Toney celebrated by holding up a shirt with a message for Brentford midfielder Sergi Canos, on loan at Olympiacos, whose mother died this week, which that read, "We are all with you Sergi"
"It's a hard game coming up now
 A big game Wednesday night
 If you want to win Premier League titles, any league title, it's how you bounce back
"It's all about timing
 At the start of the season you probably think, 'Brentford at home, not the worst' but they're bang in form and played like a good football team, a clever football team
 When they go 1-0 up you'd expect them to hold on and they didn't
"It's a massive football match on Wednesday
 I think it's make or break
 If Man City go and win the game, I don't see Arsenal coming back from that
"After today's performance, I don't see them beating Man City on Wednesday
 I'd be quite shocked
 They were so open at the back
 Played 2v2 at the back
 If Brentford had picked the right pass at times they'd have got in and won that game
"Toney misses a real good chance where he hits the bar and Man City have a better quality of player to pick that right pass
 Come Wednesday night I'd be quite shocked if Arsenal went and won that game
" "I think it was a really strong performance
 We had moments against a very tricky team to play against and credit to them as well because the results they've got against the top teams is not a coincidence
"We did a lot in the game and did the most difficult thing, to score the goal
 To concede in the way it happened is frustrating but this is the Premier League
" "Of course, we want to improve in every area
 We're the third best team in terms of defensive set-pieces in the league
 We want to be the best
"Set-pieces are Brentford's biggest strength and we controlled them quite well but in that situation, we were hoping they were going to be offside but they weren't
 Set-pieces cost you points, they are huge in this league
" "I said to players before the game that we needed our best performance because Arsenal have been so good
"We got very close to that
 I said to the boys you can't celebrate a point no matter who you are facing
 But we can celebrate a very good performance
 It was more than well deserved
" "It's insane that it's possible for us with the second lowest budget to be unbeaten and all 10 games well-deserved wins or draws, it's not like we're crawling over the line
 that's maybe even more impressive
" "I agree that when they kicked the ball, Ethan is in an offside position
"Then as far as I know the football laws, the next question is did he influence the cross? They decided it was not enough and I agree
" play  in an eagerly awaited clash at the top of the Premier League on Wednesday February 15 - kick-off 7
30pm - before travelling to Villa Park on Saturday February 19 to play Aston Villa; kick-off 12
30pm
 host  on Saturday 19 February; kick-off 3pm
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>
<PAD>