Federica Pellegrini (ITA) warmed up for a home-in-Rome response to French rival Camille Muffat's latest challenge of consistent speed (4:02, 4:03, going out in 2:04 each time on Mare Nostrum tour) with a 4:07.86 in heats of the 400m free at the Sette Colli meet this morning.
Closest to her in heats was Lotte Friis (DEN), more than four seconds away, the final holding the potential for a lonely race against the clock out front.
The finals session will feature some great action, with Ranomi Kromowidjojo (NED), on 24.66 in the 50m free heats this morning, taking on Therese Alshammar (SWE), on 24.75, and Marleen Veldhuis (NED), 24.78, later today, and Olympic champion Cesar Cielo (BRA), on 22.49 in prelims, heading the likes of Marco Orsi (ITA), Sergey Fesikov (RUS, ADN), Brazilian teammate Bruno Fratus and France's Florent Manaudou.
The 100m breaststroke features Cameron Van Der Burgh (RSA), on 1:01.06 in heats, against Fabio Scozzoli (ITA), Marco Koch (GER) and Ryo Tateishi (JPN), while Inge Dekker (NED) takes on Sarah Sjostrom (SWE) and company in the 100m butterfly, and Jason Dunford (KEN, ADN), on 52.43 this morning, races Piero Codia (ITA), on 52.67, Steffen Deibler (GER), Nikolay Skvortsov (RUS), Chad Le Clos (RSA) and Konrad Czerniak (POL).
The Seven Hills meet runs for three days until Saturday evening.