Australian rower Kim Crow only entered the single sculls at the final Olympic qualifying regatta to get some practice while her doubles partner was injured but ended up winning it and earning another London berth.

Law student Crow and Brooke Pratley had already guaranteed themselves a place in London with a silver medal in the double sculls at last year's world championships but were keen to get as much practice in competition as possible.

When Pratley suffered a rib injury, Crow entered the single sculls at the regatta in Lucerne, Switzerland as a contingency and won her heat and semi-final to take her place in the final, which she won easily on Wednesday.

"I really didn't know what to expect because everyone was racing for their lives," she told worldrowing.com.

"I have been in the single for four weeks now while my double partner has been injured. It has been really good because it shows up every single fault."

Crow's success means Australia have qualified 13 boats for the Olympic regatta at Eton Dorney from July 28 to Aug 4.