Guardiola made his senior debut on 14 October 1992 in 0–0 draw with Northern Ireland at Windsor Park in a World Cup qualifier . In the same year, Guardiola captained Spain when they won a gold medal at the Barcelona Olympic Games . It was in this year when he won the Bravo Award , voted the world's best player under the age of 21. Between 1992 and 2001, Guardiola played over 47 times and scored five goals for the senior Spain team . He was a member of the Spanish team during the 1994 World Cup , where they reached the quarter-finals, losing 2–1 to Italy . He fell out of favour with Javier Clemente , the Spain manager, due to differences and disagreement between the two, and missed out on Euro 1996 . He suffered a career-threatening injury in 1998, which kept him out of the 1998 World Cup , but he later played at Euro 2000 , where he led Spain to yet another quarter-final appearance, this time losing to France by the same margin, 2–1. He led the Spain midfield until his final appearance for la Roja , in 1–0 win in a friendly against Mexico on 14 November 2001, and scoring his last international goal against Sweden in a 1–1 draw, in his 45th appearance.  
Heavy consumption of the essential amino acid lysine (as indicated in the treatment of cold sores) has allegedly shown false positives in some and was cited by American shotputter C. J. Hunter as the reason for his positive test, though in 2004 he admitted to a federal grand jury that he had injected nandrolone.  A possible cause of incorrect urine test results is the presence of metabolites from other AAS, though modern urinalysis can usually determine the exact AAS used by analyzing the ratio of the two remaining nandrolone metabolites. As a result of the numerous overturned verdicts, the testing procedure was reviewed by UK Sport . On October 5, 2007, three-time Olympic gold medalist for track and field Marion Jones admitted to use of the drug, and was sentenced to six months in jail for lying to a federal grand jury in 2000.