Joe Cole will miss Chelsea's tour of the United States with a knee injury and is set to miss the start of the season.
The England midfielder, who hasn't played since injuring his knee in January, had minor surgery to repair a small tear in his meniscus on Wednesday and will not return to training for a month.
The setback means he is almost certainly set to miss the Community Shield against Manchester United at Wembley on August 9 and would be a major doubt for the Barclays Premier League opener against Hull City six days later.
The Chelsea squad flew out on Thursday with their four-match tour starting at the Seatle Sounders on Saturday.
The Blues then face Inter Milan in Pasadena on Tuesday, AC Milan in Baltimore on Friday week, followed by a tie with Mexican side America in Arlington, Texas two days later.
Yuri Zhirkov, the £18million signing from CSKA Moscow, was also not on the flight.
The left winger returned to the Russian capital earlier this week to secure a permit to work in England and a U.S. visa and will fly directly from Moscow to join up with the Blues in America.
Manchester City target John Terry travels as expected with Chelsea.