US will go with Caleb Dressel, Michael Phelps, Ryan Held and Nathan Adrian in tonight's showdown in the 400 free relay. No 35-year-old Anthony Ervin, whose :47.65 split in prelims earlier Sunday was the fourth-fastest split of the session. The final leg between Adrian, the defending 100 free champ and Australia's Cameron McAvoy, who swam a :47.04 at Australian trials earlier this year, will be one to watch.