Borussia Dortmund have suffered a blow on the eve of their <a href="http://www.thenational.ae/topic/events/football/champions-league">Champions League</a> semi-final against <a href="http://www.thenational.ae/topic/organisations/sports-teams/spanish-football-teams/real-madrid">Real Madrid</a> after Mario Goetze announced he was to leave for rivals Bayern Munich at the end of the season. The German international striker is set to switch to the newly crowned Bundesliga champions on July 1 for a reported EU37m (Dh180m). Dortmund confirmed that Goetze's agent, Volker Struth, had recently informed them that the player would be activating a clause in his contract to enable the move on July 1 - the first day ex-Barcelona manager Pep Guardiola takes charge as Munich coach. A statement on Dortmund's Facebook page confirmed the news, although the club stressed they had yet to hear anything official from the newly-crowned Bundesliga champions. Hans-Joachim Watzke, the Dortmund chief executive, said: "We are obviously disappointed beyond measure, but emphasise that both Mario and his advisers have behaved within the terms of the contract. "From Bayern Munich there has been nothing official on this matter up to this date." The timing of the announcement is far from ideal for Dortmund, who host Real Madrid in the first leg of their Champions League semi-final tomorrow night. But the club have asked for fans to support Gotze and the rest of the players as they seek a place in the Wembley final against Bayern or Barcelona. "Jurgen Klopp and sporting director Michael Zorc asks all fans of Borussia Dortmund to support Mario Gotze unconditionally as they would any other player in the final games of the season, but especially in the important Champions League semi-final against Real Madrid," the club said in a statement. Follow us