Schwaier was runner-up to Thomas Högstedt in the boys' singles at the 1981 US Open, the same year he also reached the Wimbledon semi-finals and made it to number three in the world junior rankings.

He reached the semi-finals at Barcelona in 1984 and en route defeated world number 14 Tomáš Šmíd, for the second time in the space of two months.

His best year was 1985, when he made his only Grand Prix final, at the 1985 BMW Open and also reached the semi-finals in Bari and Nice, as well as making it to the quarter-final stage in Basel and Indianapolis.

[2] He made his Davis Cup debut for West Germany in their 1984 World Group relegation play-off against Romania.

[3] He also played World Team Cup tennis for his country and has a win over Pat Cash to his credit, when the Australian was ranked in the top ten.