At the 2000 Summer Olympics, Klim set a world record (48.18) leading off the 4×100 m freestyle relay, which paved the way for a world record (3:13.67). Three days later, he was part of the 4×200 m freestyle relay, which set another world record (7:07.05), which left the opposition over 5 seconds in arrears on its way to victory. His 100m freestyle world record bested by Pieter van den Hoogenband in the semi's, in the final he finished with a bitter 4th place, he turned first at the wall but he claimed his legs gave away in the second half. In the 100 m butterfly, he was the world record holder, again turning first at the wall heavily under world record pace, but was cut down in the closing stages by Sweden's Lars Frölander, finishing second. On the final night he claimed silver as part of the 4×100 m medley relay team.