Raul Antonio Viver has found clay courts difficult, recording 32–50 across 82 matches (39.0%). 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): 1–1 across just 2 matches — still very early days at this level on clay.

4 quarterfinals on clay, including one run to the semifinal — regularly reaching that stage is a solid baseline, with the next step being to break through to the final rounds more often.

By format on clay — best-of-five: 8–9 (47.1%); best-of-three: 24–41 (36.9%). Significantly better in five-set matches — a strong physical profile on clay that tends to tell as matches and tournaments progress.

Best season: 1979 — 4–1 (80.0%) from 5 matches. The best single-season display to date — a useful reference point as the clay record continues to develop.