Stanislav Birner has found clay courts difficult, recording 29–61 across 90 matches (32.2%). The numbers point to a surface that has not consistently suited the game — a key area of opportunity on the calendar.

At Grand Slam level (Roland Garros): Stanislav Birner is 5–4 (55.6%) across 9 Grand Slam matches — below .500, though the elite draw depth at the Slams makes that a notoriously difficult barrier to crack.

vs. Top 10 on clay: 1–7 (12.5%, 8 matches). Top 10 opponents have represented a clear ceiling on clay; addressing that deficit is the single biggest lever for improving the overall record here.

By format on clay — best-of-five: 5–4 (55.6%); best-of-three: 24–57 (29.6%). Significantly better in five-set matches — a strong physical profile on clay that tends to tell as matches and tournaments progress.

Best season: 1981 — 6–7 (46.2%) from 13 matches. The best single-season display to date — a useful reference point as the clay record continues to develop.