Guardiola was allegedly so concerned that Piqué's performance on the pitch would be affected by his high-profile romance with the Colombian singer that he hired detective agency Método 3 to keep an eye on the defender's whereabouts and behaviour outside the Barça camp.
The Barcelona manager, who won an unprecedented 14 titles in four years while in charge of the club, also made sure other players with a reputation for misbehaving were closely monitored by the detective agency.
According to El Confidencial, Ronaldinho, Deco and Eto’o were some of the other players under investigation by Método 3, all three of whom had a reputation for partying a bit too often during their time at the Catalan giants.
"He was obsessed with the idea that his players should have quiet private lives and not go out drinking, because afterwards they would not perform on the pitch," states the report, quoting an unnamed former Barcelona employee.
Guardiola’s relationship with Piqué has been called into question in the past.
Local TV channel Telemadrid has that Guardiola asked President Sandro Rosell to get rid of Piqué if he wanted him to renew his contract as Barça manager.
Whether this is true or not, the newly appointed Bayern Munich coach once used a press conference to publicly vent his discontent about the centre-back's ongoing appearance in the tabloids, his off-key remarks and his commitment to TV ads.
“Of course I’m only leaving him on the bench for sporting reasons. I don't need to tell him what he should and should not do. He’s a grown up now.”
The 26-year-old defender, who has officially been dating Shakira since 2011, announced last January the birth of his first child with the superstar, Milan Pique Mebarak.