(Reuters) - Spaniard Rafa Nadal retired during a match for the first time in more than six years when he quit during his second-round encounter against Damir Dzumhur at the Miami Open on Saturday.
Sporadic boos greeted 14-times grand slam champion Nadal when he called it a day after seemingly feeling ill during the third set of his encounter in oppressive humidity in south Florida.
The 94th-ranked Dzumhur, of Bosnia, led 2-6 6-4 3-0 at the time, and was up 30-15 on serve.
The last time Nadal quit during a match was in a quarter-final against Andy Murray at the 2010 Australian Open.
There was no immediate comment on the exact nature of Nadal's problem, but it seemed not to be injury-related.
(Reporting by Andrew Both in Cary, North Carolina; Editing by Toby Davis)
See photos of Rafael Nadal through the years:
Rafael Nadal through the years
Nadal retires from match for first time in six years
AUCKLAND, NEW ZEALAND - JANUARY 16: Rafael Nadal of Spain eyes up a backhand return against Jiri Novak of the Czech Republic in their semi-final match at the Heineken Open in Auckland, New Zealand on January 16, 2004. Nadal knocked out the fancied Novak 6-1, 6-3. (Photo by Nigel Marple/Getty Images)
ALICANTE, SPAIN: Spain's Rafael Nadal celebrates after defeating France's Arnaud Clement in their fourth match of the Davis Cup semi final between Spain and France 26 September 2004 in Alicante. Spain advanced to the 2004 Davis Cup final taking an unbeatable 3-1 lead over France. Spain's Rafael Nadal beat Arnaud Clement 6-4, 6-1, 6-2 in two hours, 12 minutes to book a second consecutive spot in the final which they will host against the United States from December 3-5. It will be the fifth Davis Cup final for Spain who were runners-up in 1965, 1967 and 2003, and winners in 2000. AFP PHOTO / JOSE JORDAN (Photo credit should read JOSE JORDAN/AFP/Getty Images)
PARIS, FRANCE - MAY 23: Portrait of Rafael Nadal of Spain taken on May 23, 2004 during the French Open Tennis Championships at Roland Garros in Paris, France. (Photo by John Gichigi/Getty Images)
MELBOURNE, AUSTRALIA - JANUARY 20: Rafael Nadal of Spain celebrates match point against Mikhail Youzhny of Russia during day four of the Australian Open Grand Slam at Melbourne Park January 20, 2005 in Melbourne, Australia. (Photo by Clive Brunskill/Getty Images)
KEY BISCAYNE, FL - APRIL 03: Rafael Nadal of Spain wipes his brow during play against Roger Federer of Switzerland in the men's final during the NASDAQ-100 Open at the Crandon Park Tennis Center on April 3, 2005 in Key Biscayne, Florida. Federer won the match 2-6, 6(4)-7(7), 6-3, 6-1 (Photo by Matthew Stockman/Getty Images)
LONDON, United Kingdom: Rafael Nadal of Spain reacts after winning a point Irkli Labadze of Georgia during the 4th round of the Wimbledon Tennis Championships in Wimbledon, in south London, 03 July 2006. AFP PHOTO/GLENN CAMPBELL (Photo credit should read GLENN CAMPBELL/AFP/Getty Images)
Melbourne, AUSTRALIA: World number two Rafael Nadal of Spain eyes the ball as he serves during a practice session in the lead-up to the Australian Open in Melbourne, 12 January 2007. Nadal had a successful year in 2006 winning five titles including the French Open and is seeded second in this year's Australian Open. AFP PHOTO/Paul CROCK (Photo credit should read PAUL CROCK/AFP/Getty Images)
Rafael Nadal of Spain returns the ball in his game against Fernando Gonzalez of Chile during their men's tennis match on day eight of the Australian Open in Melbourne on January 26, 2009. Top seed Rafael Nadal maintained his perfect record as he swept past Chile's Fernando Gonzalez and into the Australian Open quarter-finals. Nadal, who is yet to drop a set, dominated the 2007 finalist 6-3, 6-2, 6-4 to advance to a last-eight clash with France's Gilles Simon as he seeks his first hard-court Grand Slam win. AFP PHOTO / WILLIAM WEST (Photo credit should read WILLIAM WEST/AFP/Getty Images)
Spanish tennis player Rafael Nadal (L) and Real Madrid goalkeeper Iker Casillas attend a press conference during a Red Cross media event against malaria at Santiago Bernabeu stadium in Madrid, 30 November 2007. AFP PHOTO / JAVIER SORIANO (Photo credit should read JAVIER SORIANO/AFP/Getty Images)
Spanish world number two Rafael Nadal serves to Italy's Simone Bolelli on the second day of the Qatar Open in Doha on January 5, 2010. Nadal started the 2010 ATP World Tour with a comfortable-looking draw against the world number 93 from Italy - and with his projected semi-final opponent suddenly removed. The fourth-seeded Mikhail Youzhny fell at the first hurdle against Sergiy Stakhovsky, the former US Open junior finalist, an outcome which may be more helpful to Nadal than it may at first seem, since the Russian demolished him in the opening week of the 2008 season in the Chennai final. AFP PHOTO/KARIM JAAFAR (Photo credit should read KARIM JAAFAR/AFP/Getty Images)
Spain's tennis player Rafael Nadal (2nd L) poses next to French State Secretary for Sport Rama Yade (2nd R), France's National Assembly president Bernard Accoyer and French Tennis federation president Jean Gachassin, after being awarded by the French Sports Academy with the performance of the year 2008 prize, on November 9, 2009 in Paris. AFP PHOTO / FRANCK FIFE (Photo credit should read FRANCK FIFE/AFP/Getty Images)
LONDON, ENGLAND - NOVEMBER 27: Rafael Nadal of Spain reacts during the men's singles round robin match against Novak Djokovic of Serbia during the Barclays ATP World Tour Finals at the O2 Arena on November 27, 2009 in London, England. (Photo by Clive Brunskill/Getty Images)
Spain's Rafael Nadal (L) celebrate holding the David Cup trophy next to tammate David Ferrer after winning the Davis Cup final against Argentina at La Cartuja Olympic stadium in Sevilla on December 4, 2011. Spain's Rafael Nadal got the winning point as Spain won a fifth Davis Cup. The world number two beat Argentina's Juan Martin del Potro to give the hosts an unbeatable 3-1 lead, rallying from a set down to see off the 2009 US Open champion 1-6, 6-4, 6-1, 7-6 (7/0). AFP PHOTO/JAVIER SORIANO AFP PHOTO / CRISTINA QUICLER (Photo credit should read CRISTINA QUICLER/AFP/Getty Images)
Rafael Nadal of Spain views the ball as he serves to Ruben Bemelmans of Belgium during their second round match in the ATP Thailand Open tennis tournament in Bangkok on September 30, 2010. Nadal beat Bemelmans 6-1, 6-4. AFP PHOTO/PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Spain's Rafael Nadal returns the ball to Switzerland's Roger Federer (not pictured), during their singles final tennis match, on the last day of the ATP World Tour Finals, at the O2, in south-east London on November 28, 2010. AFP PHOTO / IAN KINGTON (Photo credit should read IAN KINGTON/AFP/Getty Images)
Rafael Nadal of Spain serves during his men's finals match against Novak Djokovic of Serbia at the 2011 US Open tennis tournament September 12, 2011 in New York. AFP PHOTO/DON EMMERT (Photo credit should read DON EMMERT/AFP/Getty Images)
Spanish tennis player Rafael Nadal during a press conference of the Brazil Open in Sao Paulo, Brazil, on February 12, 2012. Nadal played in Chile winning doubles but lost his final after being away more than 7 months due to his left knee injure. AFP PHOTO/Yasuyoshi CHIBA (Photo credit should read YASUYOSHI CHIBA/AFP/Getty Images)
LIMA, PERU - NOVEMBER 17: Rafael Nadal of Spain waves to the audience after an exhibition at Jockey Club on November 17, 2013 in Lima, Peru. (Photo by Gabriel Rossi/LatinContent/Getty Images)
BEIJING, CHINA - OCTOBER 03: Rafael Nadal of Spain leaves the court after losing his match against Martin Klizan of Slovakia during during day seven of the China Open at the National Tennis Center on October 3, 2014 in Beijing, China. (Photo by Chris Hyde/Getty Images)
Tennis - French Open - Roland Garros - Paris, France - 12/06/17 - Spain's Rafael Nadal poses with the trophy near the Eiffel Tower, a day after winning the tournament. REUTERS/Benoit Tessier