Johannesburg - South Africa's marathon team for next month's IAAF World Championships in Russia was dealt a blow on Friday when Irvette van Zyl pulled out with a knee injury.
Van Zyl had been selected as a member of the women's marathon team representing South Africa at the global showpiece.
"I'm so disappointed, I really wanted to go and represent my country at the championships," Van Zyl said.
"I can't do anything with this knee at the moment -- I can't gym, I can't train and I don't know when I'll be back in action.
"I'm booked off for ten days and will test and see if I can start training after that."
Van Zyl easily achieved the qualifying mark of two hours, 43 minutes (2:43:00) for the world championships after she clocked a personal best of 2:31:26 in the London Marathon in April.
She has since struggled with synovitis (inflammation of the synovial membrane) to her right knee, which started out as a niggle during a road race in June.
"My knee started to bother me during the Durban leg of the women's 10km challenge," she said.
"I went to the doctor and nothing was detected at the time, so I started training again and it just got worse. I went back to the doctor and she found that my knee was swollen.
"I pulled back from training and only recently started training again but my knee is still very fragile."
Van Zyl hoped she would recover in time but her medical report on Friday confirmed the worst.
"Last week I got the thumbs up to run and today I just got the thumbs down," she said.
The 26-year-old almost called it quits, early in April, when an injury prevented her from training for the London Marathon.
"I was in the same injury rut after the Two Oceans but after a conversation with Rene (Kalmer), she convinced me to keep training and go and do what I do best.
"So I decided to go to London. My leg gave me trouble during the first 10k's and then after that it felt fine and I felt great in the race.
"I felt a bit tired in the last eight kms but otherwise it went well."