UEFA doping testers have made a surprise visit to Real Madrid's training session to take urine and blood samples from players including Cristiano Ronaldo.
Madrid club sources told news agency EFE that 10 players were selected at random, and all gave both urine and blood samples at Madrid's Valdebebas training ground on Thursday before passing the test.
Gareth Bale, Toni Kroos, Marcelo and Pepe were reportedly among the other individuals asked to take part by the testers, who were described as "vampires" in both AS and Marca.
Carlo Ancelotti's squad, who fly to Morocco this weekend to take part in the Club World Cup, had also been visited by UEFA's testers in the build-up to August's European Super Cup final against Sevilla.
Testers from Spain's anti-doping agency made a similar visit to Barcelona's training ground earlier in the week, with Lionel Messi also being asked to give a "double" sample, and appearing to complain via social media afterwards that he had been singled out.
After Messi's complaint earlier in the week, Agencia Espanola Antidopaje director Enrique Gomez Bastida had told AS that there was nothing unusual about the controls and that all Primera and Segunda Division squads were undergoing similar checks, which were done under guidelines handed down by the World Anti-Doping Agency (WADA).
Spanish clubs and authorities have been criticised in the past for not seriously considering the issue of potential doping in football, especially during the 2013 trial of doctor Eufemiano Fuentes, who claimed he had worked with La Liga clubs in the past.