For example, in the test match on 6 October 1983 Hauser scored all six goals as his team won 6–3 against SC Ciba-Geigy Rosental.
[12] After a turbulent time with a financially troubled FC Basel, and following the club's relegation to the Nationalliga B at the end of the 1987–88 season, Hauser transferred to local rivals BSC Old Boys.
Hauser made his debut for Sunderland[13] coming on as a substitute for Marco Gabbiadini in a 2–0 League win at Roker Park against Hull City on 25 February 1989 in front of a crowd of 14,719, following a £200,000 transfer from BSC Old Boys.
Later that season Hauser went on to feature for Sunderland in the play-off final at Wembley Stadium coming on as a substitute for Eric Gates in front of a crowd of 72,873 on 28 May 1990.
The 1990–91 season was Hauser's only in the top flight of English football, he made 10 appearances finding the net only once against Southampton F.C.
His final start, and indeed goal for Sunderland came in the League Cup in a 2–1 defeat at home to Huddersfield Town in front of only 8,161.
Hauser's final appearance for Sunderland came on Boxing Day 1991 replacing Paul Hardyman in a 1–0 defeat to Tranmere Rovers at Prenton Park.
Thomas remains a cult hero amongst the Sunderland fans who saw him battling with opposition defences at Roker Park, and is known as "The German Sub" after coming from the bench for 39 of his 65 appearances.
[1] Today he lives in Basel and is youth team trainer together with Louis Crayton (ex-FCB Goalkeeper) for BSC Old Boys.