Arsenal reopened their five-point lead at the top of the Premier League table as goals from Mikel Merino and Bukayo Saka secured a 2-0 win over Brentford at the Emirates Stadium.
Stand-in striker Merino scored for a second consecutive game as he followed up his equaliser against Chelsea with another header, this time to open the scoring from Ben White's cross in the 11th minute.
But Arsenal were made to work for the win by the dogged visitors, who almost levelled when David Raya brilliantly diverted a first-half Kevin Schade header onto the bar before Saka finally added the second in the first minute of stoppage time.
Played in on goal by the excellent Merino, substitute Saka saw his shot loop over the line despite Caoimhin Kelleher's efforts to save it, making amends for a gilt-edged miss moments earlier.
His goal came as a relief to the home fans after a nervy second half in which they had to defend a barrage of Brentford set-pieces, but the night was not without negatives for the hosts.
With first-choice centre-backs William Saliba and Gabriel Magalhaes already missing through injury, the Gunners lost a third centre-back when Cristhian Mosquera had to be withdrawn following an awkward landing during the first half.
The 21-year-old was replaced by Jurrien Timber, who partnered Piero Hincapie for the remainder of the game, but there was also a scare involving Declan Rice, who appeared to have ice on his calf after being withdrawn in the closing stages.
The victory sees Arsenal reopen their five-point lead over second-placed Manchester City, who beat Fulham 5-4 on Tuesday night, while Brentford stay 13th.
At what point does Mikel Merino come to be seen as striker who sometimes plays in midfield, rather than a midfielder who occasionally fills in up front? This was just the latest example of the 29-year-old playing the role as if a natural.
Merino has now either scored or assisted in five out of six starts up front for Arsenal since the Viktor Gyokeres injury that saw him drafted back into the role. In this game, he did both, heading home the opener, then sending Saka away for the second.
He has an astonishing total of 21 goals for club and country in the calendar year, 11 of which have come this season. His total of 14 with his head since the start of last term in all competitions is the highest by any Premier League player.
Arsenal have Gyokeres and Gabriel Jesus available again, with Kai Havertz not far behind them, but they will likely all struggle to dislodge Merino, whose value to the side is not limited to his goals and assists. His intelligence makes his team-mates better.
When he is not hunting out chances in the box, he is dropping into midfield, interchanging positions with team-mates and generally confusing opposition defences. Since his move up front a month ago, Arsenal have smashed 15 goals in six games.
Something has clicked. And it has a lot to do with Merino. A makeshift striker might just be their best option in the position right now.
Mikel Arteta said he was pleased and proud of his players after they extended their lead at the top of the Premier League table.
He told SportNews: "It is always uncomfortable because all Brentford need is a throw and it's chaos and adventure.
"One-nil is never enough against them but I thought we dominated the game and created the biggest chances.
"Overall I am very happy. The week we had, three days later without any recovery...to do that again, I'm very proud of the players."
Meanwhile, it was a fifth defeat in six away matches for Brentford.
Bees boss Keith Andrews said: "Plans don't always work out.
"We conceded an early goal and we should have done better with that. After that I felt they didn't have too many clear-cut opportunities and we grew into the game and made it uncomfortable for them.
"We gave a good account of ourselves and I'm proud of the performance."
