 He did not make his debut until 29 October of the following year, when he came on as a 59th-minute substitute for Mehmet Ekici in a 3–3 away draw against SV Sandhausen, but soon became a regular in the team, initially in midfield but subsequently in defence; he scored his first goal for the reserves on 14 February 2009, in a 2–3 loss at Dynamo Dresden.In 2010, Haas was picked by FC Bayern Munich manager Louis van Gaal for the main squad, but continued to play mainly for the B-side.He appeared in pre-season friendlies with the former, most notably the Franz Beckenbauer farewell match against Real Madrid, but, not being involved in any competitive games, moved to England on 31 January 2011 and signed for Football League Championship club Middlesbrough for an undisclosed fee.