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 | Date | Tournament | Surface | Partnering | Opponents | Score |
| --- | --- | --- | --- | --- | --- | --- |
| Winner | 1 May 2011 | BMW Open , Munich, Germany | Clay | Horacio Zeballos | Andreas Beck Christopher Kas | 7–6 (7–3) , 6–4 |
| Winner | 30 July 2011 | ATP Studena Croatia Open , Umag, Croatia | Clay | Fabio Fognini | Marin Čilić Lovro Zovko | 6–3, 5–7, [10–7] |
| Runner-up | 20 October 2012 | Kremlin Cup , Moscow, Russia | Hard (i) | Daniele Bracciali | František Čermák Michal Mertiňák | 5-7, 3-6 |
| Winner | 24 February 2013 | Copa Claro , Buenos Aires, Argentina | Clay | Fabio Fognini | Nicholas Monroe Simon Stadler | 6-3, 6-2 |
| Runner-up | 2 March 2013 | Abierto Mexicano Telcel , Acapulco, Mexico | Clay | Fabio Fognini | Łukasz Kubot David Marrero | 5-7, 2-6 |
Question:
Who was the opponent on clay surface when partnered with Horacio Zeballos?
Answer:
Andreas Beck Christopher Kas