The 1972 Monte Carlo Open was a men's tennis tournament played on outdoor clay courts at the Monte Carlo Country Club in Monte Carlo, Monaco .
 The tournament was part of the WCT Tour, which was incorporated into the 1972 Commercial Union Assurance Grand Prix circuit.
 It was the 66th edition of the event and was held from 27 March through 3 April 1972.
 Ilie Năstase won the singles title.
Marty Riessen and Sherwood Stewart were the defending champions, but Riessen did not participate this year.
 Stewart partnered Ferdi Taygan, finishing runner-up.
Brad Gilbert and Ilie Năstase were the defending champions, but Năstase did not participate this year.
 Gilbert partnered Shlomo Glickstein, losing in the first round.
The Romanian Open (also known as the BRD Năstase Țiriac Trophy) was a professional men's tennis tournament played on outdoor clay courts.
 It was part of the ATP World Tour 250 series of the ATP Tour.
 It was held annually in Bucharest, Romania, since 1993.
 Its name is taken from Romania's famous tennis players Ilie Năstase and Ion Țiriac.
Ilie "Nasty" Năstase (] , born 19 July 1946) is a Romanian former world No. 1 professional tennis player, one of the world's top players of the 1970s.
 He was ranked world no. 1 from 23 August 1973 to 2 June 1974.
Mihnea-Ion Năstase (born 7 February 1967) is a former professional tennis player from Romania.
 He is a nephew of two-time Grand Slam winner Ilie Năstase and his father, Constantin Năstase, was a Romanian Davis Cup representative.
Marty Riessen (born December 4, 1941) played amateur and professional tennis in the 1960s and 1970s.
 He was ranked as high as No. 11 in the world in singles on the ATP Rankings in September 1974, though was ranked as high as World No. 8 by Lance Tingay of The Daily Telegraph in 1971, before the computer rankings.
 Renowned for his doubles play, Riessen was also a regular doubles partner of Australian tennis great Margaret Court, winning six of his seven major mixed titles and a career grand slam alongside her.
 Additionally a winner of two men's doubles grand slams, his highest doubles ranking was No. 3 on March 3, 1980.
Tom Okker and Marty Riessen were the defending champions, but Riessen did not participate this year.
 Okker partnered Arthur Ashe, losing in the quarterfinals.
Jimmy Connors and Ilie Năstase were the defending champions, but Riessen did not participate this year.
 Okker partnered Arthur Ashe, losing in the quarterfinals.
The 2014 BRD Năstase Țiriac Trophy was a tennis tournament played on outdoor clay courts and held at Arenele BNR in Bucharest, Romania, from 21 to 27 April 2014.
 It was the 22nd edition of the BRD Năstase Țiriac Trophy tournament, and was part of the ATP World Tour 250 Series of the 2014 ATP World Tour.
 The event also futured an exhibition match with Goran Ivanišević, Cédric Pioline, Ilie Năstase and Andrei Pavel.

Question: What do Marty Riessen and Ilie Năstase have in common?
Answer: professional tennis player