British triathlete and Olympic bronze medallist Jonny Brownlee has suffered a stress fracture in his left leg.
The injury could delay his possible selection for the Olympic Games in Rio de Janeiro, Brazil in 2016.
Brownlee, 25, hopes to return before 2016 but is likely to miss some key events, including the Rio test event on 2 August and the World Triathlon Grand Final in Chicago from 15-20 September.
He said: "I'm not going to rush it because next year is a big year."
Brendan Purcell, British Triathlon performance director, said: "It's a huge blow to Jonny to get injured at this point in the season."
Winning a medal at the Rio test event and the World Triathlon Grand Final gives athletes the opportunity to earn early selection for Brazil, 2016.
Brownlee is targeting Chicago for a possible comeback but missing Rio would leave the Yorkshireman needing to perform well in next season's selection race to book his spot on the Great Britain Olympic triathlon team.
|World Triathlon Series schedule|
|7 March||Abu Dhabi||Mario Mola|
|29 March||Auckland||Jonathan Brownlee|
|11 April||Gold Coast||Jonathan Brownlee|
|25-26 April||Cape Town||Alistair Brownlee|
|16 May||Yokohama||Javier Gomez|
|31 May||London||Alistair Brownlee|
|15-20 September||Chicago - Grand Final|
The 2012 world champion, who won two of the first three world series events this year, added: "I'm obviously very disappointed. I raced really well in Auckland and the Gold Coast, and then was unlucky in London, so I was looking forward to a strong second half of the season.
"I need to focus on my rehab in the first instance and then gradually get back into some training."
Brownlee, whose brother Alistair is the Olympic champion who won the London world series race at the end of May, was training with the GB squad in St Moritz when the injury was detected before a scan in Leeds on Monday confirmed the extent of it.
Purcell added: "A scan has confirmed a stress fracture in his left femur, but it's less severe than we initially thought.
"We'll do everything we can to get Jonny back into training quickly, bearing in mind next year is a crucial year."