Question: Both Zina Garrison and Nenad Zimonjić are former or current professional athletes of what sport?
Context: Daniel Nestor and Nenad Zimonjić were the defending champions, but they split in 2011.  Daniel Nestor qualified with his new partner Max Mirnyi and Nenad Zimonjić with Michaël Llodra. Daniel Nestor and Nenad Zimonjić were the defending champions, but decided not to participate together.  Nestor partnered Max Mirnyi, while Zimonjić teamed up with Michaël Llodra.  Mirnyi and Nestor defeated Zimonjić and Llodra in the semifinals, 7–6, 7–6.  In the final, they won against Juan Sebastián Cabal and Eduardo Schwank 7–6, 3–6, 6–4 for their first Grand Slam doubles title as a team. Robert Lindstedt and Nenad Zimonjić were the defending champions but decided not to participate together.  Lindstedt played alongside Łukasz Kubot, but lost in the first round to Julien Benneteau and Édouard Roger-Vasselin.  Zimonjić teamed up with Daniel Nestor, but lost in the quarterfinals to Michaël Llodra and Nicolas Mahut. Zina Lynna Garrison (born November 16, 1963) is a former professional tennis player from the United States.  During her career, she was a women's singles runner-up at Wimbledon in 1990, a three-time Grand Slam mixed doubles champion, and a women's doubles gold medalist and singles bronze medalist at the 1988 Olympic Games.  She is currently coaching Taylor Townsend. Nenad Zimonjić (Serbian Cyrillic: , ] ; born June 4, 1976) is a Serbian professional tennis player who was ranked World No. 1 in 2008 in doubles.  He is the second tennis doubles player from Serbia to hold the World No. 1, after Slobodan Živojinović.  While Zimonjić is known as a doubles specialist (winning 3 Grand Slams in men's doubles and 5 in mixed doubles), he has recorded two big wins in his singles career.  A 22 year span consisting of 54 Davis Cup ties including 43 victories has resulted in him becoming the most accomplished Davis Cup player in his nations history.  His strongest weapon is very powerful first serve that he can hit at up to 235 km/h (146 mph). Daniel Nestor and Nenad Zimonjić were the defending champions but Zimonjić decided not to participate. <br> Julien Benneteau and Nenad Zimonjić were the defending champions, but decided not to participate together.  Benneteau played alongside Édouard Roger-Vasselin, but lost to Bob and Mike Bryan in the quarterfinals.  Zimonjić teamed up with Daniel Nestor, but lost to the Bryan brothers in the semifinals.  The Bryans became the new champions, defeating Ivan Dodig and Marcelo Melo 6–3, 3–6, [10–8] in the final. Sun Tiantian and Nenad Zimonjić were the defending champions, but Sun chose not to participate, and only Zimonjić competed that year.  Zimonjić partnered with Anna-Lena Grönefeld, but lost in the first round to Cara Black and Leander Paes. Vasek Pospisil and Nenad Zimonjić were the defending champions, but Pospisil decided not to participate.  Zimonjić plays alongside Marcin Matkowski but lost to Alexander Peya and Bruno Soares in the quarterfinals. Max Mirnyi and Nenad Zimonjić were the defending champions, but did not participate together this year.  Mirnyi partnered Mark Knowles, losing in the semifinals.  Zimonjić partnered Brian MacPhie and successfully defended his title.
Answer: tennis