Perhaps no player symbolises how much Arsenal have progressed more than Aaron Ramsey. There was a time when the midfielder was the target of such fierce criticism from a section of Arsenal's fans that Arsène Wenger wondered whether it would be best to leave him out of home matches for his own sake, but no one doubts his value now. These days the questions Wenger has to answer concern whether Ramsey will develop into one of the best players in the world after his outstanding start to the season.

It has been quite a turnaround for Ramsey, whose goal in the 1-0 win at Borussia Dortmund three weeks ago has put Arsenal in control in their Champions League group with two matches remaining. The 22-year-old has scored 11 times in all competitions but no goal has been more significant than the one in Dortmund. Marseille, who are bottom of Group F with no points, arrive at the Emirates on Tuesday night with nothing but pride to play for and a home win would put Arsenal through if Dortmund do not win at home to Napoli. If Dortmund lose, a draw would suffice.

Few predicted this scenario when Arsenal, who are likely to replace Jack Wilshere with Mathieu Flamini after the Frenchman's return from suspension, were drawn alongside Dortmund, the beaten finalists last season, and Rafael Benítez's Napoli. Yet Arsenal, the Premier League leaders and top of their Champions League group, have been busy confounding expectations and Ramsey, who has worked so hard to regain his form after breaking a leg against Stoke City in 2010, typifies their growing maturity.

"Let's not forget that one year ago people were saying to me: 'It's difficult to play him at the Emirates,'" Wenger said. "But you have to give him credit for that transformation – the credit goes to him because he could deal with that. He could come back, never give up, convince everybody that he has the needed quality.

"You could see there was an impatience with him. As a manager you think: 'Do I push him through and he can go more down or do you give him a breather to regenerate to get him a fresh start?' That's always difficult for us to assess because it is linked to their mental state. When their confidence is down they are in trouble. But he is a confident boy."

Confident enough to hit the post with a volleyed backheel in Saturday's 2-0 win over Southampton. Sitting next to Wenger, Ramsey smiled. "It was instinctive," he said. "The ball came to me at that angle so I thought: 'Why not? Have a go.'"

Wenger appreciates that ambition and imagination but stressed that Ramsey still has plenty to learn. "He's 22-years-old," he said. "I'm 64 and I still think I can improve so why should a guy who is 22 think he is at the top of his game. It's impossible. If he has the right attitude, he will continue to improve."

So will Arsenal, but they are taking nothing for granted. Even though Marseille are without the injured André Ayew and Dimitri Payet and could play several promising youngsters, Wenger pointed out that they have won their past two league matches and also refused to discuss whether Arsenal are among the tournament favourites. "If we qualify, maybe," he said.

Then again, Wenger, who said that Lukas Podolski needs another "three or four weeks" to recover from his hamstring injury after his return to training, does not mind if his side are seen as outsiders. "It's not too bad that they don't talk about us. What is important for us is that we qualify. In recent years we have not been spoiled by the draw. We didn't play Mickey Mouse teams. We played Barcelona, Bayern Munich and Milan.

"I like it that people are not talking about us because it means you can focus on what is important, which is to play well and not answer too many questions or get a false level of confidence. Just enjoy what you are really here for, which is to play football."