Arsenal defender Per Mertesacker has said he struggled to cope with the physical demands of the Premier League following his arrival at the end of the summer 2011 transfer window.
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Mertesacker, 28, was criticised for his early performances in Arsenal colours, when he appeared out of his depth in a defence that was creaking badly.
The Germany international explained that he had "needed some time" to find his feet in England, with his improved performances this season suggesting he has grown used to life in the Premier League.
"I had a very difficult first season, with all the settling in and the new things at Arsenal, but now I feel much more confident with the situation," he said.
"It is much more physical in England compared to the Bundesliga. You have to make up your mind when to make your tackles, about the way you cover your partner.
"The improvement for me has been so big after training for one year with Arsenal. This is why you can see the players who have come into Arsenal this year also need some time."
Mertesacker said Arsenal's confidence had been dented by some indifferent recent results, but that Saturday's 5-2 win against Tottenham in the North London derby had eased any nagging doubts ahead of Wednesday's crucial Champions League clash with Montpellier at the Emirates.
"We had three consecutive clean sheets at the start of the season and managed the situation well as a team, but the international breaks did not help us," he added.
"It meant we needed a great game to get our confidence back, and we had that on Saturday.
"However, there is no space for weak games now. We need complete concentration on this game against Montpellier as this is a very important game for this team to show what we can do.
"The group is still open, but we have a chance to make it clear that Arsenal go into the next round."
Mertesacker was speaking to the media alongside manager Arsene Wenger, who said: "Per has been outstanding this season.
"The problem he had last season was that he signed for us on August 31. He had no pre-season and still had to try and adapt to a different world. It was a shock for him.
"He had criticism last season, but he has shown on the pitch what he can do."