The Cubs bullpen saw another key member land on the injured list.

Lefty Luke Little was placed on the 15-day IL with a left shoulder strain and righty Ethan Roberts was recalled from Triple-A Iowa to take his place on the active roster.

Additionally, the team activated Javier Assad from the 15-day IL and will serve as the 27th man during Saturday’s doubleheader against the Cardinals. Assad is slated to start the nightcap of the twin bill.

Little, 23, suffered the injury Friday night in St. Louis, just 4 pitches into his outing. Brought in the 8th inning, with the Cubs leading 5-0, Little had a 1-2 count against Lars Nootbaar. He threw an 82-mph sweeper for a ball, winced in pain and immediately motioned to the dugout. Cubs manager Craig Counsell and trainer Nick Frangella came out and he was immediately removed from the game, replaced by Mark Leiter Jr.

The rookie was quickly developing into one of Counsell’s trusted leverage arms. Since he was recalled on May 15, Little had a 1.59 ERA with 20 strikeouts in 17 innings. His injury means the Cubs are left with just one lefty in the bullpen, veteran Drew Smyly. Counsell has used Leiter Jr. as a lefty specialist like he did Friday night in replacing Little.

Roberts, 27, has made 3 appearances this year, pitching 4 scoreless innings with 2 walks and 3 strikeouts. He made his big-league return on June 30, over 2 years after debuting with the Cubs. A shoulder injury and then Tommy John surgery kept him out of action for nearly two full years.

Assad, along with rookie Shota Imanaga, had been one of the Cubs’ best starters to begin the year. He carried a sub-2.00 ERA through his first 10 starts, helping to carry the rotation load that suffered injuries to Jameson Taillon and Justin Steele early in the season.

He struggled a bit after that, though. In his last 6 starts before landing on the IL, Assad had a 5.40 ERA in 6 starts. Assad felt pain in his forearm between starts and was placed on the IL shortly after that. He hopes to return to his early form and rejoin a starting rotation that has been dominant of late.

Cubs starters rank 6th in ERA (3.58) and 4th in WHIP (1.17) this season. Over their last 8 games, the rotation owns a 1.45 ERA and 0.72 WHIP — the Cubs are 7-1 in that stretch, including a 5-game winning streak that has brought them back into the playoff conversation.