The first night of the swimming world championship saw six world records fall and Olympic superstar Michael Phelps back on the familiar winner's podium thanks to a sprint relay upset.
The eight events of the first evening session at the Foro Italico saw six world records broken - including two in one event.
Italy's Federica Pellegrini thrilled home fans by lowering her own world mark to win the women's 400 freestyle, and German Paul Biedermann also notched a world record in winning the men's 400 free.
The Netherland's Olympic gold medal-winning women's 4 by 100 freestyle relay team lowered their world record to add a world title to their list of accomplishments - overcoming an individual 100 freestyle world record for Germany's Britta Steffen in the lead-off leg of that race.
Swedish teenager Sarah Sjostrom and American Ariana Kukors nabbed their world records in semi-finals - Sjostrom in the women's 100m butterfly and Kukors in the women's 200m individual medley.
The men's 4x100m free relay didn't produce a world record, just scintillating racing in which an American team led by Phelps and anchored by Nathan Adrian triumphed, Russia snatched silver and France's vaunted freestyle sprinters were relegated to bronze.
The record-shattering exploits were widely predicted given the current generation of high-tech supersuits.