Roger Federer has issued a public apology - doesn't everyone these days? - after ill-advisedly agreeing to a Facebook marketing stunt showing him drooling over India's World Cup shirt.

Federer's display of loyalty was to his sponsor, Nike, rather than any affinity with the Indian cricket team, but his comment "Dressing up for a gentleman's game today #BleedBlue" brought such a hostile reaction from some fans that as a non-cricket lover he could never have imagined.

Federer, a 17-times Grand Slam winner, explained: "It was more of a Nike thing to be quite honest. I met some of the Indian players and I had just spent some time in India so they presented the shirt to me. I support South Africa, and everybody knows that. The idea wasn't to spark any fire and I'm sorry if it did that."

Federer's mother Lynette is from South Africa and the Roger Federer Foundation has raised money for disadvantaged South African children.

One Pakistan supporter, a student at Cambridge University, told Pakistan's Express Tribune that he had deleted all his photos of Federer and also claimed to have taken a rudimentary opinion poll "in which ten out of 12 Pakistanis felt hurt or betrayed".

Federer's commitment to cricket sounds distinctly hit and miss. "It really depends where you are," he said. "When I'm in America definitely not. When I'm in Europe definitely not. But then when I'm in Australia and here in the UAE a little bit sometimes."

Even now, cricket fans in the United States and England (which Federer might have briefly forgotten is in Europe) are preparing to be offended.