Both Roos and Swedish record holder Axelina Johansson are aiming to become the first Swede to break the 20-metre mark. Both took part in Saturday's competition, where Roos did better.
Roos, 31, made her third throw, improving her personal best by four centimetres to 19.70.
Axelina Johansson, who holds the Swedish record in the event with 19.97, did not manage to hit the target in Eugene. Her longest throw measured 18.84, which was enough for seventh place. The winner was American Chase Jackson with 20.56.
Both Swedes have the European Championships as their main goal for the season. The championships will be held in Birmingham from August 10-16.
