Kristof Vliegen has found clay courts difficult, recording 36–47 across 83 matches (43.4%). The numbers point to a surface that has not consistently suited the game — a key area of opportunity on the calendar. Kristof Vliegen has reached 1 final without yet claiming a title on clay — one of the finest margins in tennis.

At Grand Slam level (Roland Garros): Kristof Vliegen has struggled at Grand Slam level on clay: 3–7 (30.0%) in 10 matches. The best-of-five format and elite fields make this the toughest benchmark on this surface.

ATP Masters 1000 on clay (Monte Carlo, Madrid, Rome): a positive 6–6 (50.0%) across 12 matches — winning above .500 at this level, week in week out, is a genuine sign of quality on clay.

One final reached on clay, without converting it into a title. That final-round experience is valuable groundwork for going one step further next time. 2 semifinals. 4 quarterfinals.

vs. Top 10 on clay: 1–8 (11.1%, 9 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: 7–8 (46.7%); best-of-three: 29–39 (42.6%). Slightly better in five-set matches on clay — a positive sign for the Slams specifically.

Best season: 2006 — 7–6 (53.8%) from 13 matches. The best single-season display to date — a useful reference point as the clay record continues to develop.