Question: What sport was played by both František Čermák and John Austin?

Context paragraphs:
2015 Croatia Open Umag – Doubles: František Čermák and Lukáš Rosol were the defending champions, but Čermák chose not to participate this year.  Rosol played alongside Rameez Junaid, but they lost in the semifinals to Máximo González and André Sá. <br>

2012 CNGvitall Prague Open – Doubles: František Čermák and Lukáš Rosol were the defending champions but Čermák decided not to participate. <br>

František Čermák: František Čermák (born 14 November 1976) is a Czech professional tennis player.  He has won 31 doubles titles on the ATP Tour and has been a finalist 24 times.  He achieved a career-high doubles ranking of World No. 14 in February 2010.  He usually plays doubles with Filip Polášek.  In mixed doubles, Čermák and partner Lucie Hradecká reached the final of the 2013 Australian Open and won the 2013 French Open.  In singles, Čermák won 1 Challenger title and 10 Futures titles, reaching a career-high singles ranking of World No. 201 in October 2003.

2014 French Open – Mixed Doubles: Lucie Hradecká and František Čermák were the defending champions, but Čermák chose not to participate this year.  Hradecká played alongside Mariusz Fyrstenberg but lost in the second round to the eventual champions Anna-Lena Grönefeld and Jean-Julien Rojer.

2015 Kremlin Cup – Men's Doubles: František Čermák and Jiří Veselý were the defending champions, but Veselý chose not to participate.  Čermák played alongside Radu Albot, but lost in the final to Andrey Rublev and Dmitry Tursunov, 6–2, 1–6, [6–10].

John Austin (tennis): John Austin (born July 31, 1957) is an American former professional tennis player born in Long Beach, California.  He won the Wimbledon mixed doubles championship with his sister, Tracy Austin, in 1980, becoming the first brother and sister team to win a Grand Slam title together.

2006 Estoril Open – Men's Doubles: František Čermák and Leoš Friedl were the defending champions.  Čermák did not participate this year.  Friedl partnered Lucas Arnold, finishing runner-up.

2013 Kremlin Cup – Men's Doubles: František Čermák and Michal Mertiňák were the defending champion, but they decided not to participate together.  Čermák played alongside Filip Polášek, but lost in the first round to Rameez Junaid and Philipp Marx.  Mertiňák teamed up with André Sá, but lost in the quarterfinals to Victor Baluda and Konstantin Kravchuk.  <br>

2010 MercedesCup – Doubles: František Čermák and Michal Mertiňák were the defending champions.  Čermák chose not to compete, while Mertiňák chose to play with Johan Brunström. <br>Brunström and Mertiňák lost in the quarterfinals, against Carlos Berlocq and Eduardo Schwank.

2013 Bet-at-home Cup Kitzbühel – Doubles: František Čermák and Julian Knowle were the defending champions but decided not to participate together.  Knowle teamed up with Leonardo Mayer, but lost in the first round to Daniel Brands and Michal Mertiňák. <br> Čermák played alongside Lukáš Dlouhý, but lost in the final to Martin Emmrich and Christopher Kas, 4–6, 3–6.

Supporting paragraphs: František Čermák John Austin (tennis)
Answer: tennis