Question: Thomaz Koch and Sébastien Lareau, have which occupation in common?

Context paragraphs:
1998 Advanta Championships – Doubles: Sébastien Lareau and Alex O'Brien were the defending champions, but O'Brien did not participate this year.  Lareau partnered Jeff Tarango, losing in the first round.

Sébastien Lareau: Sébastien Lareau (born April 27, 1973 in Montreal, Quebec) is a retired professional tennis player.  He became the first Canadian to win a Grand Slam title by winning the 1999 U.S. Open Men's Doubles with his American partner Alex O'Brien.

1999 Legg Mason Tennis Classic – Doubles: Grant Stafford and Kevin Ullyett were the defending champions.  Stafford chose not to participate this year.  Ullyett partnered with Piet Norval but lost in the semifinals to the eventual champions Justin Gimelstob and Sébastien Lareau.  <BR>Justin Gimelstob and Sébastien Lareau won in the final over David Adams and John-Laffnie de Jager, 7–5, 7–6.

2001 Canada Masters – Doubles: The 2001 Canada Masters – Doubles was the men's doubles event of the one hundred and twelfth edition of the Canada Masters; a WTA Tier I tournament and the most prestigious men's tennis tournament held in Canada.  Sébastien Lareau and Daniel Nestor were the defending champions but they competed with different partners that year, Lareau with Justin Gimelstob and Nestor with Sandon Stolle.  Gimelstob and Lareau lost in the first round to Mark Knowles and Brian MacPhie, as did Nestor and Stolle to Jan-Michael Gambill and Simon Larose.  Jiří Novák and David Rikl won in the final 6–4, 3–6, 6–3 against Donald Johnson and Jared Palmer.

Thomaz Koch: Thomaz Koch (born May 11, 1945 in Porto Alegre), is a left-handed former tennis player from Brazil, who was a quarter-finalist at the French Open, Wimbledon and the U.S. National Championships.

2000 Stella Artois Championships – Doubles: Sébastien Lareau and Alex O'Brien were the defending champions but they competed with different partners that year, Lareau with Daniel Nestor and O'Brien with Jared Palmer.

2000 Paris Masters – Doubles: Sébastien Lareau and Alex O'Brien were the defending champions.  Lareau did not participate this year.  O'Brien partnered Jared Palmer, losing in the semifinals.

2000 Legg Mason Tennis Classic – Doubles: Justin Gimelstob and Sébastien Lareau were the defending champions, but none competed this year.

2000 Adidas International – Men's Doubles: Sébastien Lareau and Daniel Nestor were the defending champions, but Nestor did not compete this year.  Lareau teamed up with Michael Hill and lost in first round to David Adams and John-Laffnie de Jager.

1996 Salem Open Beijing – Doubles: Tommy Ho and Sébastien Lareau were the defending champions but only Lareau competed that year with Brian MacPhie.

Supporting paragraphs: Thomaz Koch Sébastien Lareau
Answer: tennis player