Olympic and world champion Ruta Meilutyte had surgery on a broken elbow after falling off her bicycle.
The Plymouth-based Lithuanian, 18, suffered the injury on Friday and had the operation on Monday.
"It's going to be a four-week process before she's back in the water doing regular-type swimming," her coach Jon Rudd told BBC Sport.
"It's not too desperate at all with us being well over 40 weeks away from the Olympic Games."
"It's not ideal, but the good news is it's happened at the beginning of the season," Rudd added.
"We'd already started work for the Olympics much earlier than we would for any regular season.
"We'd been on a training camp for 10 days in Lanzarote before we came back to Plymouth and she was back in training for two or three days here as well before the accident happened.
"So we had two weeks in the bank that we wouldn't normally have.
"The most important thing is to get things right for the summer, and I'm confident by the time we get to July, September will be a very distant memory and we'll be where we think we should be."