Question: Barbara Jordan and Mark Knowles are both what?

Context paragraphs:
2013 SAP Open – Doubles: Mark Knowles and Xavier Malisse were the defending champions but Knowles did not participate this year because of his retirement from professional tennis in September 2012. <br>

Mark Knowles: Mark Knowles (born 4 September 1971) is a former tennis player from the Bahamas, specialising in doubles tennis.  He has won a number of Grand Slam tournaments, most notably partnering with Daniel Nestor.  At various times between 2002 and 2005 he was ranked World No. 1 in doubles.  He is a five-time Olympian.

2008 Stella Artois Championships – Doubles: Mark Knowles and Daniel Nestor were the defending champions, but Knowles chose not to participate, and only Nestor competed that year.

2002 RCA Championships – Doubles: Mark Knowles and Brian MacPhie were the defending champions but they competed with different partners that year, Knowles with Daniel Nestor and MacPhie with Nenad Zimonjić.

2005 Mutua Madrileña Masters Madrid – Doubles: Mark Knowles and Daniel Nestor were the defending champions and successfully defended their title, defeating Leander Paes and Nenad Zimonjić 3–6, 6–3, 6–2 in the final.  It was the 39th doubles title for Knowles and the 41th doubles title for Nestor, in their respective careers.  It was also the 4th and final title of the year for the pair.

2008 French Open – Men's Doubles: Mark Knowles and Daniel Nestor were the defending champions, but did not compete together.  Knowles partnered with Mahesh Bhupathi, but lost in the first round to Stephen Huss and Ross Hutchins.

2010 Rogers Cup – Men's Doubles: Mahesh Bhupathi and Mark Knowles were the defending champions, but they chose to not compete together this year.  Bhupathi played with Max Mirnyi and Knowles partnered with Radek Štěpánek.

Barbara Jordan (tennis): Barbara Jordan (born April 2, 1957) is a former professional female tennis player from the United States who won the 1979 Australian Open singles title.

2001 If Stockholm Open – Doubles: Mark Knowles and Daniel Nestor were the defending champions but only Knowles competed that year with Brian MacPhie.

2007 Davidoff Swiss Indoors – Doubles: Mark Knowles and Daniel Nestor were the defending champions, but Nestor chose not to participate, and only Knowles competed that year.

Supporting paragraphs: Barbara Jordan (tennis) Mark Knowles
Answer: former tennis player