Alistair Brownlee may be forced to write off this year's first three World Triathlon Series races as he continues his comeback from an Achilles tear.
The world champion said his recovery is going well ahead of the Olympics but he is not yet running at full intensity.
Brownlee, 23, missed last week's Sydney race and will not race in San Diego in three weeks. He may also abandon plans for a comeback in Madrid next month.
"I'm probably going to struggle with Madrid," Brownlee told BBC Sport.
"I'll have to make the decision whether I want to race just to get a race in, even though I'm not particularly fit, or I decide I'm only going to race when I'm fully fit - which I'm definitely not going to be by then.
"My swimming's fine and my biking's great but running's always going to be the big one with an Achilles injury.
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The Brownlees have installed an underwater treadmill at their Yorkshire home to help Alistair with his recovery.
"I can tell you now there's no chance I'm going to be 100%. Realistically, even optimistically, I'll have done two weeks of decent training before Madrid. I could go and race all right but if I'm not there, it's because I've decided I don't want to go and race just 'all right'."
Younger brother Jonny, the world number two behind Alistair, also skipped the Sydney opener to the eight-stage series which decides triathlon's world title over the Olympic distance. Helen Jenkins came second in the Sydney women's race for Great Britain, but the event had never been on the Brownlees' agenda.
Jonny will travel to San Diego for 12 May and is expected to race in Madrid on 27 May, a tough course favoured by the Brownlee brothers.
San Diego had been Alistair's initial target for a return but he has not raced since revealing his Achilles injury in February and may now not compete again until June.
World Triathlon Series
- San Diego
- (Olympic race, London 7 August)
Alistair denied pushing his comeback any nearer to August's Olympic triathlon in London's Hyde Park would damage his bid for gold, but admitted he needs race experience before the Games.
"I'm trying to get to the point where I can train fully [and at the moment] I'm not doing the really hard, intense stuff," he said.
"If in the next three or four weeks I can get to the point where I'm training what I'd call a normal week, and then do that for four or five weeks, I'll be pretty close to my maximum fitness.
"Then I've got another five or six weeks after that before the Olympics. So, if nothing else goes wrong, there's absolutely no reason why I can't be in great shape.
"Your first race [after an injury] tends to be your more nervous one where you're trying to feel things out. Ideally you wouldn't want to stand on the Olympic start line with that being your first race of the season."