Ruben Loftus-Cheek vowed to come back strong after the Chelsea midfielder confirmed the surgery on his ruptured Achilles tendon was a success.
Loftus-Cheek suffered the injury during Chelsea's 3-0 friendly win against the New England Revolution in Boston on Wednesday.
Chelsea are yet to put a timescale on his return, but he will miss the Europa League final against Arsenal on May 29, as well as England's Nations League Finals campaign in Portugal in June.
Goal understands Loftus-Cheek is expected to miss five and nine months of action, which could see him sidelined for much of the first half of the 2019-20 season.
The 23-year-old said he is struggling to describe his emotions but promised to come back fit and firing.
"Difficult to describe how I'm feeling right now, more confusion than sadness," Loftus-Cheek wrote.
"My surgery went very well so I'm off to a good start! I'll be watching from the sidelines for a little while now so I wish the boys all the luck in the Europa League final and of course the Nations League Finals.
"Coming back strong from an injury is something I've had to do all my life and I'll do it again."
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Despite faring well on loan in the 2017-18 season that saw him make England's World Cup squad, Loftus-Cheek began this season out of Maurizio Sarri's plans, relegated to primarily Europa League action at the start of the campaign.
However, Loftus-Cheek made the most of those opportunities, and began staking a larger claim to playing time in the Premier League for the Blues in November and December.
The midfielder would go on to make six starts in the top-flight and 24 total appearances for the Blues in the league, scoring six goals and adding two assists.
He added another four goals and three assists in the Europa League, over 11 appearances (eight starts) in Chelsea's run to the final.
Loftus-Cheek's campaign mirrors the season of his team-mate Callum Hudson-Odoi, who also broke through into Sarri's plans as the season went on through strong performances, only to be felled late in the year by a torn Achilles.