Michael Ballack looks set to leave Bayer Leverkusen when his contract expires at the end of the season. The former Chelsea midfielder has revealed he never intended to remain at the club, which he joined 18 months ago, for more than two years. The 35-year-old took his time to settle in to his spell at Leverkusen, but has emerged as a key player this season, captaining the team regularly. \"I signed on here for two years and it was clear for both parties from the very beginning that it was only planned for this period of time,\" he told Germany\'s Sky Sports News channel. \"I then intended to do something different.\" Ballack has yet to decide on the next step in his career, although retirement is not currently in his mind. \"I am not going to give up playing altogether,\" he added. \"I have never said that. I still have six more months to consider my situation and I will do that without any pressure.\" Leverkusen appear resigned to losing the former Germany captain in the summer. \"It is highly likely that Michael will leave us at the end of this season,\" the club\'s general manager Wolfgang Holzhauser was quoted as saying by Kicker at their training camp in the Algarve today. \"But certainly nothing is absolutely definite - there is rarely anything definite in football,\" he went on. \"But in my eyes, there is little to suggest that Michael will extend his two-year contract anymore.\" Holzhauser admits losing Ballack would be a major blow to his club. \"Michael is in excellent shape,\" he said. \"He will certainly be able to play on at the highest level.\" Ballack has been linked in the German press with a move to free-spending Wolfsburg.