Ten-man Arsenal produced a performance of strength and character to chisel out a 1-0 win at Sunderland on Saturday.
The crucial goal came after 36 minutes when Santi Cazorla drilled home a low shot through a crowded area.
But the points were won in the final half-hour when, following the dismissal of Carl Jenkinson, Arsène Wenger's men repelled incessant attacks from the home side.
Behind them Wojciech Szczesny was superb. The Polish keeper pulled off two vital saves from Steven Fletcher and his handling was exemplary as his goal came under ferocious fire.
This magnificent victory pushes Arsenal up to fifth and they will stay there if Everton fail to win at leaders Manchester United on Sunday.
But this result meant much more than that. It was a response to Tottenham's crucial victory earlier in the day and it suggests that Wenger's men have the stomach for a fight to secure a top-four finish in the final few months of the season.
This was arguably the most satisfying afternoon of the season so far.
Before kick-off there was late drama in the Arsenal line-up. Laurent Koscielny was named on the team-sheet but was troubled by his calf in the warm-up so Jenkinson stepped up from the bench.
Sagna was switched to centre back to accommodate the Englishman on the right of the defence. Elsewhere Ramsey came into central midfield and Cazorla began on the left.
Abou Diaby and Alex Oxlade-Chamberlain moved to the bench.
This was the second north London v north-east game of the day. Tottenham’s narrow 2-1 win over Newcastle in the lunchtime kick-off put pressure on the visitors at the Stadium of Light.
They would respond in superb style.
The start was breakneck. Alfred N’Diaye guided a header over at one end, Theo Walcott cut inside and drove at the keeper at the other.
Minutes later Olivier Giroud set up Walcott again but his shot was batted away by Simon Mignolet.
Stephane Sessegnon beat Nacho Monreal on the right but Jenkinson booted away the dangerous low ball into the area.
Then Giroud emerged on the left-hand side of the area but dragged his shot across the face of goal.
We had only played 15 minutes but there had been enough clear-cut chances for an adequately-entertaining first-half.
As we reached the midway point, the game started to settle a little.
And Arsenal started to take over.
On the half-hour, Jack Wilshere set up Ramsey to left fly from just outside the area. It looked a certain goal but Mignolet threw himself to his right to save.
The visitors were putting a squeeze on Sunderland and, in the 36th minute, they burst through.
Giroud and Walcott set up Cazorla to drive home his ninth league goal of the season through a thicket of legs in the area.
The strike was all the impetus Arsenal needed and they utterly dominated the game until the interval.
Giroud cut the ball back for Walcott in the D. He managed to get away a powerful drive but the effort whistled just side.
In the dying minutes, Arsenal might have take the game by the throat when Giroud nudged Ramsey clear eight yards out.
Mignolet spread himself Schmeichel-like and managed to block.
The start of the second half was different. Both midfields changed – Sebastien Larsson came on for Sunderland, Abou Diaby replaced the injured Wilshere for Arsenal.
The home side were more aggressive and imposing. But the visitors had the best chances.
Giroud and Cazorla both weaved into space on the on the left of the area and dragged inquisitive efforts past Mignolet’s left-hand post with the keeper stranded.
In between those key efforts, Sessegnon robbed Ramsey in midfield and led a three-on-three break. He fed Fletcher but the Scottish striker dragged his drive into the sidenetting.
The game had been much more even in the second half but the sending off of Jenkinson swung the game towards the hosts.
The right back clipped Sessegnon as the Benin international flew down the left. He had already been booked, a second yellow was inevitable.
Suddenly Sunderland were everywhere and Martin O’Neill brought on striker Danny Graham to add to their firepower.
Sagna hooked the ball away from the waiting Jack Colback and Sessegnon made a nuisance of himself on the left.
Arsenal still had chances. Cazorla went close from distance and, in the 75th minute, the Spaniard sent Walcott scuttling through.
The Englishman burst clear and clipped the ball past Mignolet but it bounced ball of the woodwork. A crucial moment.
Five minutes later, Per Mertesacker’s clearance was charged down by Fletcher and, with the big German appealing for handball, the Scotsman’s shot was saved superbly by Szczesny.
The Arsenal keeper was now crucial to the hopes of his side as the game was now one-way traffic. The Pole responded superbly.
Five minutes later, he made a stunning tip over from Fletcher's point-blank header.
In the final 10 minutes, Szczesny caught cleanly or punched firmly when anything came in his area. And a lot did.
He also made a magnificent sprawling save from Adam Johnson's raking cross-shot. Before that Titus Bramble had fired wide
Arsenal had moments going forward - Cazorla and Giroud blazed over, Diaby went close - but this was a rearguard action.
The height of Diaby and Giroud was vital as Sunderland fired corner after corner, free-kick after free-kick, cross after cross into the danger area.
At full time the Arsenal players high-fived, slapped backs and hugged. This had been a victory crammed with character and it keeps Wenger's team hot on the heels of Tottenham for a place in the top four.
- Jenkinson Yellow Card Red Card
- Wilshere 50
- Walcott 87 Yellow Card
- Cazorla Goal!
- Miquel 87
- Diaby 50
- Rose 81
- Cattermole 46 Yellow Card
- N'Diaye 68
- Colback Yellow Card
- Larsson 46 Yellow Card
- Vaughan 81
- Graham 68