The Springbok Women blew the Eagles away with a breathtaking diap[ly of attacking rugby in the first half at Ellis Park on Saturday.

Springbok Women's coach Swys de Bruin believes his side's second-half lapse against the USA may ultimately prove more valuable than their blistering first-half display after South Africa opened their two-Test series with a convincing 34-21 victory at Ellis Park on Saturday.

The Bok Women overwhelmed the higher-ranked Americans before half-time, racing into a 29-0 lead with an inventive, fearless brand of rugby that left the visitors with few answers. But after extending their advantage to 34-0 shortly after the restart, South Africa lost momentum as the Eagles scored three unanswered tries to give the final scoreline a far more respectable look.

"We played a brilliant first half – the best half of rugby I experienced with this team since I joined them," said De Bruin. "That was perfect rugby, so I cannot be too hard on them because we allowed USA back into the game in the second half. Remember, the Eagles are a very good team in their own right."

Rather than viewing the second-half fade as a disappointment, De Bruin said it may prove one of the biggest positives from the opening Test.