Tony Blair left his Italian counterpart Silvio Berlusconi hobbling after a "friendly" football game, it has been reported.
Mr Berlusconi greeted the Blairs wearing a mystery bandana
The pair played a five-a-side game at the Italian's Sardinian home during Mr Blair's visit earlier this month.
Having taken an accidental knock to the knee, Mr Berlusconi was left with a noticeable limp, the Italian newspaper La Repubblica said.
The Italian leader saw a specialist as the pain worsened, it was reported.
Touching his leg, the centre right politician supposedly joked: "You know, the left is always giving me problems."
Mr Blair apparently ran into Mr Berlusconi during what was described by La Repubblica as a ginochiata, or "knee thrust", leaving his counterpart with a damaged cartilage.
Football fanatic Mr Berlusconi, who owns Serie A club AC Milan, was reportedly whisked off to hospital after returning from an official visit to Libya.
Downing Street said anything that had happened on holiday would be a "private matter".
Mr Blair has often played in impromptu football matches and days before had stunned locals in a match involving his earlier host Prince Girolamo Strozzi in the Tuscan town of San Gimignano.
In 1995, he famously played header tennis for the cameras with Kevin Keegan, manager of the team he supports, Newcastle United.
Mr Blair often exercises early in the morning and works out several times a week using a gym running machine.
Despite a heart scare last year Mr Blair says he has no difficulty in switching off from his job, citing tennis, swimming, football with the kids and playing his guitar among his pastimes.