Didier Drogba has undergone a "successful" operation on his fractured arm, but the Ivory Coast star's World Cup participation remains in doubt.The Chelsea striker broke a bone close to his elbow during his side's 2-0 friendly win over Japan on Friday.The Ivory Coast Federation (FIF) said they and the surgeons who performed the procedure "are confident regarding the speedy recovery of the player".However, they did not say how long Drogba was likely to remain out for.Speaking prior to Drogba's surgery at the Lindenhof hospital in Berne, coach Sven-Goran Eriksson told BBC Radio 5 live there was still a chance the talismanic 32-year-old could feature in South Africa.Eriksson's side kick off their campaign against Portugal on 15 June, followed by games against Brazil (20 June) and North Korea (25 June) in a group many observers consider the tournament's most competitive.The Ivorians' chances of emerging from that 'Group of Death' would be massively hampered by any Drogba absence.The scorer of 44 goals in 69 appearances for his country and the Premier League's top goalscorer last season, Drogba had opened the scoring against the Japanese in Sion, Switzerland, with a 13th-minute deflected free-kick.After his 16th-minute injury exit, which resulted from a clash with defender Marcus Tulio Tanaka, the Elephants went on to win the game 2-0 with Manchester City defender Kolo Toure netting the second.Afterwards, Eriksson refused to blame Tanaka for the incident."It was unlucky," said the former England boss. "It wasn't bad or stupid. He didn't want to hurt anyone. Football is a game of contact."The Swede must now anxiously wait for another update on Drogba's condition, while World Cup organisers will also hope it's positive news for the African superstar, whose possible absence would be a significant blow to the tournament.Source: BBC