Arsenal's Jekyll and Hyde season rolls on. Nervy, vulnerable and disjointed until half-time, they scored four times in 11 scintillating second-half minutes to demolish West Ham.
To borrow a favourite phrase from Arsene Wenger, the handbrake was off and it was a truly magnificent sight.
The Premier League cannot have seen anything better this season.
It must be maddening, then, for Wenger to gaze at the league table and see a team capable of such brilliance still down in sixth place, albeit now only four points behind Tottenham in fourth.
With Theo Walcott and Jack Wilshere maintaining their high standards of recent months, this was an evening when Wenger's three most recent signings, Lukas Podolski, Olivier Giroud and Santi Cazorla, really shone.
The best goal of the night was a toss-up between Cazorla's exquisite back-heeled finish and a Podolski piledriver. The German winger produced the outstanding performance. As well as scoring Arsenal's first, he provided three assists.
A mini-injury crisis in central midfield had forced Wenger to recall Aaron Ramsey in an unfamiliar anchor role in front of the defence, with Wilshere and Cazorla granted licence to push further forward and support Giroud.
With Arsenal so short of bodies in that area, there was immediate concern when Wilshere turned his left ankle in the third minute after a challenge with Jack Collison.
Wilshere continued following lengthy treatment but, with Mikel Arteta and Francis Coquelin injured, Wenger would still like to add a holding midfielder this month. West Ham rested one of his main targets, Mohamed Diame.
Arsenal's midfield were the first to assert themselves, with Wilshere bisecting West Ham's defence only for Ricardo Vaz Te to make a wonderful recovering tackle to deny Walcott.
Arsenal's initial flurry, however, was short-lived. In West Ham's first period in the opposition half, they forced two corners and Arsenal wobbled.
From the second, delivered by Matthew Taylor, Giroud could head his clearance only to the edge of the penalty area. Collison was waiting and unleashed a wonderful strike past Wojciech Szczesny.
West Ham's lead did not last long. After a swift interchange of passes between Wilshere and Cazorla, the ball was fed to Podolski as he drifted into space from the left. West Ham were slow to react and duly punished by a 20-yard finish of exceptional power past Jussi Jaaskelainen.
The goal eased the tension but Arsenal's football remained disjointed, with slick passages of passing involving Cazorla, Walcott and Wilshere punctuated by moments of defensive uncertainty.
While Arsenal held the upper hand, West Ham also looked capable of scoring at any time.
That was evident from another setpiece when Taylor's inswinging freekick beat the entire Arsenal defence but narrowly evaded Carlton Cole.
Arsenal's uncertainty was also evident in front of goal. Having got behind the West Ham defence with a brilliant combination of passes, Kieran Gibbs' crossed just too far in front of Podolski. Joey O'Brien cleared his scuffed finish off the line.
Arsenal needed a goal-line clearance to retain parity. Bacary Sagna's header had bounced off Taylor to put Cole clear but Szczesny got just enough on the ball to slow its progress and allow Ramsey to clear.
Wenger's half-time talk enhanced Arsenal's gathering momentum. Having quickly forced a corner, Walcott surprised West Ham by aiming the ball short to Giroud, who got sufficient contact to direct the ball inside Jaaskelainen's near post.
With a clever flick, Giroud then released Podolski down the left. It looked like Cazorla would be smothered by the bodies in the six-yard box but, showing breathtaking improvisation, he adjusted his feet and back-heeled the ball beyond the helpless Jaaskelainen.
Arsenal were now in full flow, with Podolski continuing to embarrass Winston Reid at right-back. Podolski's sweeping cross found Walcott at the back post. He scored his 16th goal of the season with a clinical shot.
Arsenal were still not finished, with Wilshere again feeding Podolski, who produced another pinpoint delivery for Giroud to score his second and Arsenal's fifth.
A miserable evening for West Ham was compounded when Daniel Potts had to be carried off on a stretcher following a collision with Sagna that required nine minutes of medical treatment.
His departure left West Ham down to 10 men. By then, Arsenal's emphatic victory was secure. (© Daily Telegraph, London)