The opening day's prelims of the inaugural LEN U23 Championships saw American Gabriel Jett produce a lifetime best in the men's 100m fly for the top seed.
Ireland's Ellen Walshe will tackle the women's 100 fly and 200 IM on the opening night of the LEN U23 European Championships in Dublin, seeded second in both.
Dimitrios Markos sat back in 7th place at the midway point of the race before making his move with sub-27 splits on the third and fourth lengths of the pool.
Several swimmers including Patrick Sammon have scratched out of their events at the Pro Championships after having been named to the LEN European U23 team.