Fragile at home, fearless on the road, Arsenal are difficult to fathom.
Arsene Wenger's mystery men
Champions tend to be defined by certain characteristics. There are the unbeatable and the unstoppable, the irrepressible and the imaginative, the ruthless and the relentless. They do not tend to be noted enigmas.
Yet the theme of Arsenal's season is its sheer mercurialness. This is a side that offers radically different conclusions on a weekly basis.
If they win at Aston Villa today they will top the Premier League, if only for a couple of hours, but such have been the mood swings in a strange season that even the most one-eyed Gunner would struggle to imagine a straightforward procession to the title.
This is a Jekyll and Hyde side. A split personality has been apparent in previous years, but now there is an unexpected role reversal. Arsenal are fragile at home and fearless on the road. They are passing tests of character and failing examinations of competence. No Premier League team can rival their away record; none, however, have lost more matches on their own turf.
Their schizophrenia was showcased in the space of 90 seismic minutes last week. Tottenham Hotspur were played off the park in a first half of sumptuous skill. Yet they emerged victorious after a second period when Arsenal folded.
Perhaps it was a consequence of a complacency that can be the product of youthful talent demonstrating its clear superiority, perhaps a result of Harry Redknapp's tactical changes and motivational prowess. Yet the most concerning conclusion is an old criticism: Arsenal have a soft underbelly.
The manner of Tottenham's derby winner - Younes Kaboul heading in a free kick from Rafael van der Vaart - renewed suspicions about their set-piece defending. Given the delivery of Ashley Young and the height of John Carew and Richard Dunne, it is likely to be examined again today.
The performance of the commanding William Gallas painted his successor in the Arsenal defence in an unflattering light. Laurent Koscielny displays an elegant wiriness in possession, but looks lightweight and naive out of it.
Arsenal's twin personas are epitomised by Lukasz Fabianski, the goalkeeper capable of brilliance or blundering. Blameless in the back-to-back defeats to Tottenham and Braga, he was at fault when Newcastle United won at the Emirates Stadium three weeks ago. Yet the Pole has excelled in each of Arsenal's last three wins on their travels.
They go to Villa Park minus their catalyst, the hamstrung Cesc Fabregas. Villa can testify to his influence; in December, they were heading for a stalemate in London before Arsene Wenger, the Arsenal coach, introduced his semi-fit skipper. The Spaniard duly delivered a brace before limping off.
Arsenal's improved away results suggest others are assuming a greater responsibility. A more forceful Samir Nasri, in particular, has impressed in midfield and Marouane Chamakh has provided the physical presence that had been lacking in attack.
Yet there is an imbalance in resources. Even minus Fabregas, Wenger has an abundance of options in the final third: any of Theo Walcott, Tomas Rosicky, Jack Wilshere and Robin van Persie could come in for the captain, even if it prompts a reshuffle, but the defensive choices are less enticing.
Shorn of Thomas Vermaelen, Emmanuel Eboue and, perhaps, Gael Clichy, a makeshift back four may encounter the man voted Arsenal's sixth greatest player.
Robert Pires is likely to make his home debut for Villa, probably as a replacement, against a team who, if Clichy is out, will not contain a single member of 2004's Invincibles. That was a team built on irresistible attack and solid defence.
Today's men are more of a mystery. It makes for unpredictability, but silverware seems rather less certain.
4.45pm, AD Sports 3 & 5