Arsenal have advanced since their last meeting with Bayern Munich, but even that only offers small comfort.

In the relentless quest for self-improvement that underpins all of his work, the European champions have found in Pep Guardiola the means to refine and enhance their own accomplishment. A Champions League tie between the two clubs tonight promises football of style and grace, but it will also be brutally revealing. Ambitions will be exposed for all that they are worth.

When the two clubs met at the same stage in last season's competition, Bayern won the first leg at the Emirates with such domineering aplomb that the 3-1 scoreline seemed an inaccurate reflection of the game. Arsenal regrouped, although their 2-0 win in Germany owed much to Bayern slackening off in the comfort of their first-leg advantage.

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The outcome was a revelation to Arsenal. They had encountered a team of power and industry that had mastered the balance between pressing and harrying to retain possession then unleashing quick and scathing attacks. A new power was establishing itself in the game and their qualities were a challenge to Arsenal.

It is the differences that illuminate the clubs' encounter at the Emirates tonight. Arsenal are more bullish, a harder edge has been added to their technical expertise, while Bayern have in Guardiola a new manager who was able to take command of the team that won the treble last year and improve it.

After losing that first leg 12 months ago, Arsenal found a surge of form that provided the momentum to raise them to the status of Barclays Premier League title challengers, and they have only been defeated on seven occasions in that time. Yet Bayern have only lost twice in the same period, with only one defeat this season under Guardiola. In the Bundesliga, they are unbeaten in 46 games and have won 13 consecutive matches.

Teams run aground against Bayern, since Guardiola has added variety and intensity to a side that was already mercilessly effective. Moving Philipp Lahm from full-back to a defensive midfield role was considered a drastic solution, but it was merely in keeping with the theory that underpins Guardiola's work: outnumber opponents in the midfield to control the game.

The Spaniard did not remodel Bayern in the style of his previous club, Barcelona, but instead evolved as a coach. It has become a defining moment - because it is so often repeated - that he instructed his centre-backs to play long balls upfield against Borussia Dortmund earlier in the season, to counter the pressing style of Jurgen Klopp's team. Guardiola was misunderstood as an idealist, though.

Tactical adjustments are made throughout games and preparations to maximise the chances of victory. Arsenal tried the same last season, when Theo Walcott played the central striking role against Bayern at the Emirates, to use his pace to force the defensive line back. It did not work, but Arsene Wenger, the Arsenal manager, will trust in a sense of adventure, nonetheless. There are decisions to be made on playing Alex Oxlade-Chamberlain or Tomas Rosicky as one of the three attacking midfielders behind Olivier Giroud, but what will be critical is the team's willingness to believe itself capable of prevailing against a team pushing for a place in posterity.

Arsenal lost to Dortmund at home in the group stages, although won in Germany. There have been league victories over Liverpool and Tottenham Hotspur, but also defeats by Liverpool, Manchester City, Manchester United, and a failure to beat Chelsea in either the league or the Capital One Cup. For almost a decade, Arsenal have been able to justify missing out on trophies with the promise of a financially-sound future once the Emirates was paid for. Having mounted a title challenge this season, and knocked Liverpool out of the FA Cup last weekend, as well as qualifying from a Champions League group that contained Dortmund, Napoli and Marseille, a time of judgement has arrived.

Wenger needs to send out a team that can resist Bayern, but also impose themselves. A cold assessment would consider the task beyond them. Bayern once coveted Wenger, but now have in Guardiola a figure who could influence managerial thinking for a generation. He has out-thought Wenger before, when Barcelona defeated Arsenal at this stage of the competition in 2011, and they seem even now to be on separate paths.

Bayern are attempting to become the first club to retain the trophy since it was rebranded as the Champions League, while Arsenal are striving to end a run of three consecutive seasons in which they have been knocked out at this stage. There are similarities in the way that the two teams rely on technical refinement and a deliberate elegance on the ball, and differences in the way they react to opponents being in possession. Ultimately, though, this is a tie that will reveal what these two teams are capable of this season.