As the decathlon began, it was defending Olympic champion Ashton Eaton who emerged as the leader at the halfway point at the Rio Olympics.
"It's not awful", Warner said, after the 400-metres, where he struggled in the heat and dropped from second to third.
Ashton Eaton of the US during the men's decathlon shot put in the Rio 2016 Summer Olympic Games at Estadio Olimpico Joao Havelange on August 17.
"That's the thing with the decathlon - you just never know", Warner said.
Eaton, going for his second Summer Games gold, leads the competition with 2,803 points, just 27 fewer than when he reset his own world record in Beijing at the World Outdoor Championships last summer.
Ashton Eaton is looking to win his second straight gold medal in the decathlon at the Olympics, and he's looking strong so far in his efforts. If an athlete is a bit off in one event, he can hope to make it up in another. It takes 10 to win.
According to a story from The New Yorker published yesterday, Tate Metcalf, Eaton's high school coach, saw potential in his young athlete and believed Eaton's best path to a Division I college was through the decathlon.
"If they go well, that's great, you're on a roll; if they don't, you have some other psychological challenges". Eaton widened his lead after the shot put event as well, with Warner throwing the shot only a disappointing 13.66 metres - well behind his personal best of 14.74 metres.
Warner earned 1,023 points for the victory while Eaton, who is married to Canadian heptathlete Brianne Theisen-Eaton, recorded 985.
But Warner, who cleared his opening heights with perfection all the way to 2.04, didn't react to his rival's misfortune. "It's up to me", said Warner, who finished fifth in the 2012 London Games.
In the long jump, the native of London, Ont., leaped 7.67 metres to collect 977 points.
The women's 100-meter hurdles finals is also Wednesday at 9:55 p.m. with the semifinals kicking off at 7:45 p.m. Brianna Rollins, Nia Ali and Kristi Castlin will be representing Team USA.