US and Jamaica set up another women's sprint relay showdown

EUGENE, Ore. : The United States landed the first blow in the "phoney war" of the women's 4x100m relay on Friday as their shadow squad qualified fastest for the final, with perennial rivals Jamaica solid enough but with so much more to come.

The U.S. squad of Melissa Jefferson, Aleia Hobbs, Jenna Prandini and Twanisha Terry were spot-on with their changeovers to come home well clear in the second of two heats.

The Americans clocked 41.56 seconds and have some quicker individuals to bring in for Saturday's final.

The Jamaican shadow squad did what was needed, getting the baton safely round to finish second behind Britain in 42.37 in the first heat.

Jamaica's "big three" - Shericka Jackson, Shelly-Ann Fraser-Pryce and Elaine Thompson-Herah - who swept the 100m podium and raced the 200m final on Thursday, were all rested.

Jamaica and the United States have each won four of the last eight world titles and between them took eight of the last 10 Olympic golds.

They will need to avoid any changeover fumbles to continue that run though as Britain, regulars on the podium in global competitions over the last decade, also looked good.

Daryll Neita ran an impressive anchor after a succession of sharp changeovers as they posted 41.99 seconds and they have Dina Asher-Smith to come into the team.

Spain and Italy both clocked national records to advance, along with Germany, Nigeria and Switzerland.