Once the major league leader in home runs allowed, Dan Haren had allowed just four homers in 50 innings since coming off the DL.
Haren hadn't allowed more than two runs in an outing since July 22.
In the first inning of this afternoon's game alone, Haren allowed two homers and four runs, and the Nationals trail 4-0 early.
Alex Gordon got things started for the Royals with a solo shot to right leading off the bottom of the first.
Emilio Bonifacio then came around to score from first on a weird play, which saw a ball deflect off Ian Desmond's glove and roll into shallow center. Three batters later, Salvador Perez crushed a two-run shot to left, and Haren suddenly trailed by four runs.
Haren has talked countless times over the last handful of weeks about how keeping the ball down has allowed him to avoid the homers and the big innings. He didn't do that in the first, leaving a fastball over the plate to Gordon and a splitter up to Perez, and he got burned.
The Nats had a big comeback win against the Royals on Friday, turning a 6-0 deficit into an 11-10 win.
They'll need another one of those comebacks in order to leave Kansas City with a sweep.
Update: Ian Desmond now has two homers in as many games. And today's blast traveled a long ways.
Desmond smoked a 2-1 fastball from Ervin Santana off the facing of the Royals Hall of Fame on the left field concourse, a bomb that traveled 431 feet, according to the Royals.
The Nats' shortstop had just three homers in a 45-game span going into yesterday's game. He now has two in his last four at-bats.
The Royals' lead has been trimmed to three, thanks to the Desmond homer. It's now 4-1 after four, as Haren has found a way to settle in, scrapping through three scoreless frames since his four-run first.