Lamback finished sixth in the 400-meter freestyle finals with a time of 4:56.07. Josef Craig, a 15-year-old swimmer from Great Britain, won the event with a world-record time of 4:42.81. Craig bested the world record he set in the heats by almost three seconds.
The 26-year-old Lamback was almost three seconds faster in the finals than in the heats, when he finished seventh. Earlier this week, he won a gold medal in the 50-meter free.
Lamback still has one more event this week. He will compete in the 4x100 medley relay Saturday.