Wasn't it 12-0 and 2 wins on clay?
Edit: it was 10-0, sorry.
10-0, 4-0 on clay.
Stefan Edberg 10-0 Thomas Muster
1986 Gstaad R32: Stefan Edberg def. Thomas Muster (6-3, 7-6)
1988 Forest Hills R16: Stefan Edberg def. Thomas Muster (6-4, 6-3)
1990 World Team Cup RR: Stefan Edberg def. Thomas Muster (6-2, 6-4)
1994 Australian Open QF: Stefan Edberg def. Thomas Muster (6-2, 6-3, 6-4)
1994 Monte Carlo QF: Stefan Edberg def. Thomas Muster (6-7, 7-6, 6-4)
1995 Indian Wells QF: Stefan Edberg def. Thomas Muster (2-6, 6-4, 6-1)
1995 Davis Cup QF: Stefan Edberg def. Thomas Muster (6-4, 6-2)
1996 Queen's Club SF: Stefan Edberg def. Thomas Muster (6-7, 6-3, 6-2)
1996 Vienna R16: Stefan Edberg def. Thomas Muster (6-4, 6-7, 7-5)
1996 Paris Indoor R32: Stefan Edberg def. Thomas Muster (6-2 ret.)
Walkover match
1989 Australian Open QF: Thomas Muster def. Stefan Edberg (Walkover)