Question: Elena Likhovtseva and Serena Williams, have which occupation in common?

Context paragraphs:
2008 Australian Open – Mixed Doubles: Elena Likhovtseva and Daniel Nestor were the defending champions, but Likhovtseva chose not to participate, and only Nestor competed that year.

2005 Uncle Tobys Hardcourts – Doubles: Svetlana Kuznetsova and Elena Likhovtseva were the defending champions, but Kuznetsova did not compete this year.  Likhovtseva teamed up with Magdalena Maleeva and successfully defended her title, by defeating Maria Elena Camerin and Silvia Farina Elia 6–3, 5–7, 6–1 in the final.

2007 J&amp;S Cup – Doubles: Elena Likhovtseva and Anastasia Myskina were the defending champions, but Myskina chose not to compete that year.  Likhovtseva partnered with Elena Vesnina.

2000 Adidas International – Women's Doubles: Elena Likhovtseva and Ai Sugiyama were the defending champions, but had different outcomes.  While Likhovtseva teamed up with Amanda Coetzer and lost in first round, Sugiyama teamed up with Julie Halard-Decugis and successfully defended her title by defeating Martina Hingis and Mary Pierce in the final, 6–0, 6–3.

Serena Williams: Serena Jameka Williams (born September 26, 1981) is an American professional tennis player.  The Women's Tennis Association (WTA) has ranked her world No. 1 in singles on eight occasions, from 2002 to 2017.  She became the world No. 1 for the first time on July 8, 2002.  On the sixth occasion, she held the ranking for 186 consecutive weeks, tying the record set by Steffi Graf for the most consecutive weeks as world No. 1 by a female tennis player.  In total, she has been world No. 1 for 319 weeks, which ranks her third in the Open Era among female tennis players.  Some commentators, players and sports writers regard her as the greatest female tennis player of all time.

2008 Moorilla Hobart International – Doubles: Elena Likhovtseva and Elena Vesnina were the defending champions, but Likhovtseva chose not to participate, and only Vesnina competed that year.

Elena Likhovtseva: Elena Alexandrovna Likhovtseva (Russian: Елена Александровна Лиховцева ] ; born 8 September 1975) is a Russian former tennis player.  She turned professional in January 1992 at the age of 16.

2003 WTA German Open – Doubles: Elena Dementieva and Janette Husárová were the defending champions, but had different outcomes.  Dementieva had to withdraw due to a left foot strain, while Husárová teamd up with Elena Likhovtseva and reached the semifinals.

2004 Toray Pan Pacific Open – Doubles: Elena Bovina and Rennae Stubbs were the defending champions, but had different outcomes.  While Bovina did not compete this year, Stubbs pertnered with Cara Black and successfully defended her title, defeating Elena Likhovtseva and Magdalena Maleeva 6–0, 6–1 in the final.  It was the 2nd title in the year for the pair, and the 14th title for Black and 44th title for Stubbs, in their respective careers.

2003 Wimbledon Championships – Mixed Doubles: Mahesh Bhupathi and Elena Likhovtseva were the defending champions, but played in this year with different partners.  Bhupathi teamed up with Paola Suárez and lost in third round to Nenad Zimonjić and Iroda Tulyaganova, while Likhovtseva teamed up with Bob Bryan and lost in second round to Andy Ram and Anastasia Rodionova.

Supporting paragraphs: Elena Likhovtseva Serena Williams
Answer: professional tennis player