Merritt's 2008 season was distinguished by a considerable rivalry with Wariner, who had won the 400  m at every major global championship since 2004. The 2008 IAAF Golden League provided the venue for many of their duels. He scored his first major win over Wariner in a close affair at the Internationales Stadionfest in Berlin. He confirmed his Olympic place a month later by winning at the 2008 United States Olympic Trials, again defeating the reigning Olympic champion Wariner. Later in July at the Golden Gala meeting, Wariner responded by edging a win in the 400  m by just 0.01  seconds. At the Meeting Gaz de France in Paris, the last Golden League competition before the Olympics, Wariner seemed to have the momentum behind him after a win in 43.86  seconds.