[1] Haas played with GC for seven seasons before moving to England to join Premier League club Sunderland in August 2001.

On 30 August 2002 it was announced that Haas had joined Basel's first team during their 2002–03 season under head coach Christian Gross, who in the meantime had moved on.

[3] Haas played his domestic league debut for the club in the home game in the St. Jakob-Park on 11 September 2002 as Basel won 7–1 against Wil.

They ended this in third position behind Manchester United and Juventus, but ahead of Deportivo La Coruña.

[5] Haas scored his first goal for the club on 8 March 2003 in the home game as Basel won 2–0 against Servette.

[6] Although Basel had a buy out option in the loan contract, Hass decided he wanted to return to England.

[17][18] That season's top scorer Joaquín Ardaiz and his fellow Uruguayan Agustín González had made appearances in 21 games without a valid work permit.

[20] He has a twin sister named Dina, once a talented sports photographer and well known in the football business.