Butch Seewagen has found clay courts difficult, recording 24–35 across 59 matches (40.7%). 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): 1–2 across just 3 matches — still very early days at this level on clay.

By format on clay — best-of-five: 1–4 (20.0%); best-of-three: 23–31 (42.6%). Markedly stronger in three-set formats; the win rate drops noticeably in five-setters, which has direct implications for Grand Slam performance on clay.

Best season: 1968 — 3–3 (50.0%) from 6 matches. The best single-season display to date — a useful reference point as the clay record continues to develop.