WASHINGTON -- Before the Reds and Nationals went into a three-hour, four-minute rain delay before the start of the bottom of the fourth inning on Wednesday at Nationals Park, starting pitcher Jeff Hoffman’s night was already over. Hoffman exited with right shoulder soreness after tossing just 1 1/3 innings and walking five batters.

Hoffman was placed on the injured list on Thursday with what manager David Bell said was a right shoulder impingement. In corresponding moves, the Reds recalled lefty Cionel Pérez from Triple-A Louisville and appointed right-hander Art Warren as the 27th player for Thursday's second game.

Hoffman, 28, returned to Cincinnati for examinations.

"It’s not going to require surgery," Bell said. "He’s going to have an aggressive rehab on it and try to get back as quick as he can.”

How the Reds replace Hoffman's spot in the rotation is unclear. Vladimir Gutierrez will be called up from Triple-A Louisville to make a spot start on Friday -- and his big league debut -- against the Cubs. Wade Miley is eligible to return from the 10-day IL on Sunday and is expected to start that day's game at Wrigley Field.

"We obviously have to make a decision before long, but it hasn’t been made yet," Bell said.

The game was suspended with the Reds trailing by three runs, and they were unable to climb out of that hole when the game resumed Thursday afternoon, losing, 5-3. The originally scheduled night game will feature starter Sonny Gray on the mound in a seven-inning contest. Pérez was on the active roster for the suspended game.

Twenty-five pitches into the game, the Reds were down a run. With the bases loaded, Nationals catcher Alex Avila drew a walk in a seven-pitch at-bat, resulting in the second run crossing the plate. Reds pitching coach Derek Johnson approached the mound in an attempt to refocus his starter. One pitch later, the inning ended on a groundout.

Wednesday marked Hoffman’s 10th start of the season. The 2014 first-rounder made 38 starts with the Rockies before joining the Reds this offseason in the deal that sent Robert Stephenson to Denver. The 1 1/3 innings marks the shortest start of the right-hander's career.

Of Hoffman's 46 pitches tossed, 29 of them were four-seamers -- the velocity dropping 1.4 mph from his yearly average, which has also dropped compared to last season. The starter could not locate his pitches, receiving just four called strikes, only one of which was entirely inside the true strike zone.

Averaging just over 4 1/3 innings pitched across his 10 starts, Hoffman has been unable to help in a department where his team has been in dire need: quality starting pitching. Only nine times this season has a Cincinnati starter earned a quality start.