Nationals pitcher John Lannan clutches his face after being hit in the face by a line drive against the Colorado Rockies in the fourth inning. (Patrick Smith/Getty Images)

The Washington Nationals had made winning one-run games virtually routine over the past month and a half. No matter how dire circumstances seemed, they managed to collect the required hit, hold an opponent at bay with their lively bullpen arms or manufacture any combination thereof.

Suddenly, though, that trend has taken a unsettling turn following a 3-2 loss to the Colorado Rockies before 19,046 at Nationals Park on Friday night. Now the Nationals have dropped two in a row by the narrowest possible margin after their previous 10 wins had come by one run or in extra innings.

“We don’t go out there down by one and just expect to win it,” second baseman Danny Espinosa said. “You just go out there, and you continue to play and fight hard, and hopefully you get some guys on, have an opportunity to score some runs. Tonight it didn’t go our way.”

The Rockies’ three-run fourth inning dealt Washington (45-45) its first losing streak of this 10-game homestand heading into the all-star break. To make matters worse, starting pitcher John Lannan was hit in the face by a batted ball and knocked from the game on the same day the team placed catcher Ivan Rodriguez on the 15-day disabled list and announced promising reliever Cole Kimball is scheduled for season-ending surgery on his right rotator cuff.

Lannan had been humming along into the fourth when Rockies left fielder Ty Wigginton connected on a hard line drive that hit the left-hander on the nose. Lannan immediately fell to his hands and knees, covered his face with his cap and wasted no time walking to the dugout as team trainer Lee Kuntz tended to what the team called a nasal contusion.

Because the all-star break begins Monday, Lannan might not miss a start, Manager Davey Johnson said after the game.

“It’s a manager’s worst nightmare,” Johnson said. “We’re very fortunate that there wasn’t more damage. That ball was smoked, and thing is he got his glove up to deflect it off, so it wasn’t too bad.”

The ball eventually trickled into center field, allowing Jonathan Herrera to score from second to tie the score at 1. The single, which came two batters after Herrara’s hard liner up the middle also whizzed by Lannan’s head, ended what was shaping up to be another productive outing for one of the National League’s most efficient starters during the last six weeks.

Over his previous eight starts dating from May 27, Lannan was 3-0 with a 1.92 ERA. In his five no-decisions during that span, he was in line for the win three times, and his 1.96 ERA in June ranked eighth in the league among qualified starters.

Before departing under inauspicious circumstances against Colorado (42-47), which snapped a five-game losing streak, Lannan also appeared on his way to perhaps a career day in strikeouts. Normally a groundball pitcher, Lannan had fanned five through three-plus innings, including three in a row and four of five in one stretch. The Nationals’ first out of the fourth came via Lannan’s final strikeout of the game.

Then, following singles from Herrera and Todd Helton, Wigginton stepped into the batter’s box and drilled Lannan’s 1-1 fastball right back at him. Ryan Mattheus entered in relief, and the right-hander got Mark Ellis to ground to the mound. Mattheus fielded it and threw to second, where shortstop Ian Desmond was covering, to get the force out.

Ellis, though, wound up safe at first, and Helton advanced to third before coming home for a 2-1 lead when Mattheus was called for a balk while facing Cole Garner. Ellis made it 3-1 on Garner’s single to left field, but a base-running miscue left Garner caught in a rundown that ended the inning.

The Nationals trimmed the deficit to one in their half of the fourth courtesy of Wilson Ramos’s two-out homer, his eighth, that landed roughly a dozen rows deep in the Red Porch seats in left center. Ramos is three home runs short of the most in a season by a Natonals catcher.

Washington was unable to get more than one runner on in any subsequent inning, although Morse led off the ninth with a single that dropped in front of diving center fielder Carlos Gonzalez. Bixler came in to pinch run, but he was thrown out trying to advance to second moments after Jayson Werth struck out swinging on a pitch in the dirt. Rick Ankiel ended the game by striking out swinging as well, also on a pitch catcher Chris Iannetta had to block.

“We got thrown out in some situations that I didn’t really like,” Johnson said. “But Bix was just being aggressive late, and the ball bounced. I like that instinct. It was a well played ballgame, other than the fact I lost my starting pitcher.”