For the second straight September, the Phillies are facing the possibility of reaching the playoffs with a top-line starting pitcher on the injured list.

Jesus Luzardo was placed on the injured list Tuesday, interim manager Don Mattingly said ahead of a game in Washington. Luzardo was scratched from his last start with left shoulder stiffness and has not responded to treatment as was hoped.

The move is retroactive to Sept. 12, leaving Luzardo eligible to come off on the last day of the regular season, Sept. 27. The National League Wild Card Series will begin Sept. 29.

Luzardo has been spectacular this season, with a 14-5 record and 2.87 ERA in 29 starts. An All-Star, he’s coming off a complete-game shutout against the Atlanta Braves on Labor Day. Since May 14, Luzardo has a 1.93 ERA and 164 strikeouts in 135 innings. The Phillies are 18-3 in his last 21 starts.

The Phillies originally announced they were going to recall right-hander Grant Holman, who gave up four unearned runs in his only outing this season against Atlanta last weekend. But an hour later, they amended that to promote lefty Kyle Backhus, who has a 4.95 ERA in 21 appearances this year and a 2.84 ERA in 24 games at Triple A.

Neither is a starting option, which will likely require a bullpen game at some point during a four-game series against the Mets in New York this weekend, then again in a season-closing six-game homestand against Milwaukee and Tampa Bay.

Luzardo was great in the postseason last year for a short-handed Phillies staff.

He allowed three hits and two earned runs in six innings in Game 2, then returned to allow two hits and one unearned run in 1.2 innings three days later, though he was saddled with the loss in both. The Phillies signed him to a five-year, $135 million extension in the offseason.

There are echoes to last fall, when Zack Wheeler was diagnosed with blood clots and underwent thoracic decompression surgery, ruling him out of the postseason.

The Phillies still have Wheeler, Cristopher Sanchez and resurgent Aaron Nola and Andrew Painter to toe the rubber in the postseason, should they get there.

The Phillies enter play Tuesday 4½ games behind Atlanta in the National League East. They are in the second Wild Card spot, a half-game behind Chicago and one game up on San Diego, but four in the loss column ahead of Arizona to make the postseason.