Horacio Zeballos has found hard courts difficult, recording 31–52 across 83 matches (37.3%). The numbers point to a surface that has not consistently suited the game — a key area of opportunity on the calendar. Horacio Zeballos has reached 1 final without yet claiming a title on hard — one of the finest margins in tennis.

At Grand Slam level (Australian Open & US Open): Horacio Zeballos has struggled at Grand Slam level on hard: 2–11 (15.4%) in 13 matches. The best-of-five format and elite fields make this the toughest benchmark on this surface.

ATP Masters 1000 on hard (Indian Wells, Miami, Canada, Cincinnati, Shanghai, Paris): Horacio Zeballos is 10–12 (45.5%) across 22 Masters matches — below .500 in the Tour's deepest fields. Lifting that record here would unlock better results across the whole hard swing.

One final reached on hard, without converting it into a title. That final-round experience is valuable groundwork for going one step further next time. 1 semifinal. 3 quarterfinals.

By format on hard — best-of-five: 2–11 (15.4%); best-of-three: 29–41 (41.4%). Markedly stronger in three-set formats; the win rate drops noticeably in five-setters, which has direct implications for Grand Slam performance on hard.

Best season: 2009 — 5–4 (55.6%) from 9 matches. The best single-season display to date — a useful reference point as the hard record continues to develop.