New Arsenal face an old question of credibility in San Siro

Remodelled since winning in Milan in 2008, for all their consistency – and prize-money – Wenger's side are yet to claim a European title

It is notable that from the Arsenal team that won 2-0 at San Siro almost four years ago, only Bacary Sagna is likely to play tonight. Abou Diaby and Manuel Almunia were in the side four years ago but have drifted off to the periphery through injury and form. Theo Walcott came on as a substitute in 2008. The rest who played then have gone.

It was an extraordinary victory, all the more so because 10 months earlier Milan had won the Champions League, defeating Liverpool in the final in Athens. In 2008, Arsenal drew the home leg against Milan 0-0 but held out in Italy two weeks later to score two goals – from Cesc Fabregas and Emmanuel Adebayor – in the final six minutes. It was the last time the Gunners eliminated a major Champions League team in the knockout rounds of the competition.

Of that starting XI, four – Adebayor, William Gallas, Gaël Clichy and Philippe Senderos – are still playing in the Premier League, with the first three of that quartet now at clubs placed above Arsenal in the table. Fabregas, Mathieu Flamini, Emmanuel Eboué and Aleksandar Hleb have all left the club and not all of them, it should be said, have gone on to bigger and better things.

On the more positive side, Robin van Persie was an unused substitute in March 2008 and has developed into a crucial player since then. Thierry Henry may too have some role to play tonight in his last game on loan from the New York Red Bulls – by 2008 he was in his first season at Barcelona. But the feeling remains that the team that knocked out Milan four years ago was a stronger side than the one Arsène Wenger will field in the sub-zero temperatures of San Siro tonight.

There is the usual collection of injury problems for Wenger, including the most recent, to Per Mertesacker, who will miss the next few weeks. Jack Wilshere, Diaby, Carl Jenkinson and Andre Santos are all out which means that Kieran Gibbs will, in all likelihood, have to come straight back into the team tonight.

The game also asks a wider question about Arsenal in the Champions League. They are undoubtedly consistent, especially given the failure of the two Manchester clubs to reach the knockout stages. Yet no one really expects Arsenal to win the competition this year.

Milan are marginally the bookmakers' favourites to prevail over two legs but it is too close to call. Given the manner in which the power of Italian club football has been on the wane for the four years since these two teams last played – Serie A goes down to three Champions League places next season – Arsenal might have been expected to have made greater strides over that period relative to Milan.

The Gazzetta dello Sport newspaper yesterday carried a table of total earnings for clubs from the Champions League over its entire 20 years. Arsenal were placed fifth, on €298.9m (£190m at current rates), the highest of any club that has not won the tournament and second only among Premier League rivals to Manchester United. Their staying power is admirable even if it has largely been characterised by mediocrity.

Since beating Milan, Arsenal have eliminated Roma (2009) and Porto (2010) in the knockout stages and they won the first leg at home against Barcelona last year. They have earned more Champions League prize-money in the last two decades than the likes of Milan, Liverpool, Internazionale and Porto – but unlike those three clubs they have not yet won the competition.

The team has changed dramatically with, Van Persie aside, an almost entirely different group of senior players from the one in place in 2008. The likes of Jens Lehmann, Kolo Touré (who both played in the first leg four years ago), Gallas, Clichy, Flamini, Fabregas, Eboué and Adebayor have all gone. In some respects, for the better – but it puts into perspective the scale of the change Arsenal have undergone.

As a presence in the tournament, Arsenal's threat is diminishing. Having eliminated Milan in 2008, Arsenal were knocked out in the quarter-finals by Liverpool. They peaked the following year with a semi-final place, eventually beaten by Manchester United. In 2010, they only got as far as the quarter-finals and last year it was the first knockout round at which they bowed out, both times to Barcelona.

The Champions League is an intriguing distraction for Arsenal but by the time the second leg against Milan arrives on 6 March – after a ludicrously long interim of three weeks, including an international break – they will have a much clearer idea of where the season is going. Henry will be gone. Their FA Cup tie with Sunderland will be resolved and they will have faced Tottenham (home) and Liverpool (away) in the league.

Wenger said last night that he still backs his team to win whoever they play. "If I thought that we had no chance to win the game, then I would stay at home," he said at his press conference in San Siro. Yet the FA Cup looks a much more realistic prospect for Arsenal to win this season.

In the Premier League they are now ahead of Chelsea in fourth place on goals scored, which means that going into two significant league games, and with Chelsea in a very bad moment, Wenger's team are once again well placed to make a strong finish for the top four. Given their problems at the start of the season, that is not really a bad place to be.

There is every chance that, over two legs, Arsenal could see off Milan again and, as he did in 2008, Wenger will pay tribute to his young players' ability to compete on the biggest stages. That, however, is still a long way from winning what would be the club's first trophy since 2005.

Milan v Arsenal first leg: Three key confrontations

Thiago Silva v Robin van Persie

Thiago has an unenviable task in nullifying Premier League top scorer Van Persie. Milan conceded eight in the group stages, but the Brazilian has been excellent in central defence this season, and has the athleticism and awareness to make life difficult for Arsenal's 27-goal talisman.

Clarence Seedorf v Mikel Arteta

Arteta's metronomic and accurate distribution has been a welcome addition to Arsenal and four-time Champions League winner Clarence Seedorf is the man charged with disrupting the Spaniard's rhythm. The veteran Dutchman's leadership and experience will be crucial for Milan.

Zlatan Ibrahimovic v Thomas Vermaelen

Ibrahimovic has two goals in 14 Champions League games against English sides – but both came against Vermaelen and Arsenal for Barcelona in 2010. The Swede will find it hard against Arsenal's defensive bedrock.