Duvall was ultimately credited with a two-run single on the bizarre first-inning play in Wednesday night's 9-2 win over the Arizona Diamondbacks. It happened because Riley thought the ball had been caught.
With runners on first and third and one out, Duvall hit a deep fly ball off Merrill Kelly. Arizona center fielder Jake McCarthy leaped near the wall, and the ball deflected off his glove and into the first row of seats.
Riley, thinking McCarthy had the ball in his glove, retreated to first base as Duvall passed him between first and second. Duvall was ruled out at second on what's known as a "runner's fielder's choice." Freddie Freeman and Riley scored on the play to give Duvall 109 RBIs this season, which leads the National League.
"I wasn't sure [McCarthy] didn't catch it," Braves manager Brian Snitker said. "You may be making the right play, but if the guy in front of you doesn't, you've got to be aware of it. It's not a bad rule at all."
Duvall has 15 home runs with the Braves since being acquired from the Miami Marlins in July.
Baseball historians might point out that Duvall is not the only Braves hitter to ever lose a three-run homer because of a baserunning mistake.
Back in 1959, Harvey Haddix of the Pirates took a perfect game into the 13th inning against the Milwaukee Braves at old County Stadium. With the score 0-0, an error put the Braves' leadoff man on base, ending the perfecto, and Hank Aaron was intentionally walked with one out.
Slugger Joe Adcock then hit a drive over the fence for an apparent three-run homer. Aaron, however, thought the ball was still in play -- when he saw the runner ahead of him score, he trotted off the field. Adcock, meanwhile, rounded the bases.
The umpires counted Adcock's homer and said the final score was 2-0. NL president Warren Giles later ruled Adcock should only be credited with a double and made it a 1-0 final.
The Associated Press contributed to this report.