Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Outcome | Tournament | Surface | Opponent | Score |
| --- | --- | --- | --- | --- |
| Winner | Louisville , US | Hard (i) | Donald Young | 0–6, 7–5, 6–3 |
| Runner-up | Kyoto , Japan | Carpet (i) | Go Soeda | 6–7 (0–7) , 6–2, 4–6 |
| Runner-up | Freudenstadt , Germany | Clay | Simon Greul | 3–6, 4–6 |
| Winner | Loughborough , UK | Hard (i) | Frederik Nielsen | 6–3, 3–6, 6–1 |
| Runner-up | Pingguo , China | Hard | Go Soeda | 4–6, 5–7 |
| Winner | Athens , Greece | Hard | Dmitry Tursunov | W/O |
| Runner-up | Nottingham , UK | Grass | Gilles Müller | 6–7 (4–7) , 2–6 |
| Runner-up | Granby , Canada | Hard | Édouard Roger-Vasselin | 6–7 (9–11) , 6–4, 1–6 |
| Runner-up | Helsinki , Finland | Hard | Daniel Brands | 6–7 (2–7) , 6–7 (5–7) |
| Runner-up | Geneva , Switzerland | Clay | Marc Gicquel | 6–3, 3–6, 4–6 |
Question:
Which opponent used a grass surface?
Answer:
Gilles Müller