Question: Who was born first, Alex O'Brien or Frederik Nielsen?

Context paragraphs:
Alex O'Brien: Alex O'Brien (born March 7, 1970 in Amarillo, Texas) is a retired professional tennis player from the United States, who competed on the ATP Tour.  He became the world No. 1 doubles player in May 2000 and was ranked as high as world No. 30 in singles in June 1997.

Frederik Nielsen: Frederik Løchte Nielsen (born 27 August 1983) is a professional male tennis player.  He is a former Wimbledon Men's Doubles champion, in 2012, and now competes mainly on the ATP Challenger Tour in both singles and doubles.  Nielsen is coached by fellow Dane John Larsen and is a member of the Denmark Davis Cup team.  His grandfather is former grand slam finalist Kurt Nielsen.

2015 Aircel Chennai Open – Doubles: Johan Brunström and Frederik Nielsen were the defending champions, but Nielsen chose not to participate.  Brunström played alongside Nicholas Monroe, but lost in the first round to Roberto Bautista Agut and Stan Wawrinka. <br>

2016 Tiburon Challenger – Doubles: Johan Brunström and Frederik Nielsen were the defending champions but only Nielsen chose to defend his title, partnering Noah Rubin.  Nielsen lost in the first round to Blaž Rola and Grega Žemlja.

2015 Fairfield Challenger – Doubles: This was the first edition of the tournament, Johan Brunström and Frederik Nielsen won the title defeating Carsten Ball and Dustin Brown in the final 6–3, 5–7, [10–5].

2013 Wimbledon Championships – Men's Doubles: Jonathan Marray and Frederik Nielsen were the defending champions, but decided not to play together.  Marray played alongside Colin Fleming, but lost to Robert Lindstedt and Daniel Nestor in the third round.  Nielsen paired up with Grigor Dimitrov, but lost to Julien Benneteau and Nenad Zimonjić in the second round.

2010 USTA LA Tennis Open – Doubles: Harsh Mankad and Frederik Nielsen were the defending champions, but Nielsen chose not to compete this year.Mankad partnered up with Samuel Groth, but they lost in the semifinals against Brian Battistone and Nicholas Monroe. Battistone and Monroe won in the final 5–7, 6–3, [10–4] against Artem Sitak and Leonardo Tavares.

2012 Wimbledon Championships – Men's Doubles: Bob Bryan and Mike Bryan were the defending champions, but lost to wildcards Jonathan Marray and Frederik Nielsen in the semifinals.  Marray and Nielsen won the title defeating fifth seeded Robert Lindstedt and Horia Tecău who competed in their third consecutive Wimbledon final.  Marray became the first British player to win the men's doubles at Wimbledon since Pat Hughes and Raymond Tuckey in 1936.  Nielsen is only the second Danish winner of a Grand Slam title, following his own grandfather, Kurt Nielsen, who won the mixed doubles at the 1957 U.S. National Championships.

2017 Odlum Brown Vancouver Open – Men's Doubles: Treat Huey and Frederik Nielsen were the defending champions but chose to defend their title with different partners.  Huey partnered Robert Lindstedt but lost in the final to James Cerretani and Neal Skupski.  Nielsen partnered Andreas Siljeström but lost in the semifinals to Huey and Lindstedt.

2013 Intersport Heilbronn Open – Doubles: Johan Brunström and Frederik Nielsen were the defending champions but Nielsen decided not to participate. <br>

Supporting paragraphs: Frederik Nielsen Alex O'Brien
Answer: Alex O'Brien