Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_23 (opponents VARCHAR, surface VARCHAR, partnering VARCHAR)
### Question:
Who was the opponent on clay surface when partnered with Horacio Zeballos?
### Answer:
SELECT opponents FROM table_name_23 WHERE surface = "clay" AND partnering = "horacio zeballos"