|Country|| West Germany
|Born||15 December 1969
|Height||6'4" (193 cm)|
|Highest ranking||No. 321 (2 Mar 1992)|
|Highest ranking||No. 138 (2 Oct 1989)|
Despite winning two Grand Prix doubles titles, Haas never competed in the main draw of a Grand Slam event. He did however make some Grand Slam appearances in the juniors. The biggest tournament he participated in as a singles player was the 1991 German Open, part of the ATP Super 9 series. He lost in the first round to Omar Camporese from Italy. The only occasion that he made it past the opening round of a Grand Prix or ATP Tour tournament was in the 1991 Kremlin Cup, where he defeated Soviet Sergej Skakun, before being eliminated in the second round by Jakob Hlasek.
He won his first doubles title at Frankfurt in 1988, partnering a 17 year old Goran Ivanišević. They upset the reigning Australian Open champions Rick Leach and Jim Pugh in the semi-finals, then defeated Jeremy Bates and Tom Nijssen in the final. The other title win was in Palermo the following year, with he and partner Peter Ballauff beating both the first and second seeds.
Grand Prix career finals
Doubles: 2 (2–0)
|Outcome||No.||Year||Tournament||Surface||Partner||Opponents in the final||Score in the final|
|Winner||1.||1988||Frankfurt, West Germany||Carpet||Goran Ivanišević|| Jeremy Bates
|1–6, 7–5, 6–3|
|Winner||2.||1989||Palermo, Italy||Clay||Peter Ballauff|| Goran Ivanišević
|6–2, 6–7, 6–4|
|No.||Year||Tournament||Surface||Partner||Opponents in the final||Score in the final|
|1.||1992||Fürth, Germany||Clay||Udo Riglewski|| Brian Joelson