Luke Little, a promising rookie in the Cubs' bullpen, experienced a setback on Friday night during a stellar performance. Little left the Cubs series opener against the St. Louis Cardinals in the 8th inning, just four pitches into his outing.

Facing Lars Nootbaar on a 1-2 count, Little unleashed an 82.6 mph sweeper that resulted in a ball. However, he immediately winced and motioned to the Cubs' dugout, signaling that something was wrong. Manager Craig Counsell and trainer Nick Frangella rushed to the mound to assess the situation, ultimately leading to Little's exit from the game.

Following the game, Counsell described the issue as "shoulder discomfort" for Luke Little. This setback comes at a crucial moment for the Cubs, who will need to manage 18 innings in a doubleheader on Saturday, followed by the series finale on Sunday before the All-Star break.

Luke Little has proven to be a valuable asset since his recall on May 15. In 19 outings since then, he has showcased his skills with an impressive 1.59 ERA, recording 20 strikeouts and holding opposing batters to a meager .127 batting average in 17 innings. Little, along with Porter Hodge, has established themselves as key components of the Cubs' bullpen.

Mark Leiter Jr., who replaced Little on the mound after the injury, stepped up with two strikeouts to finish the inning. Leiter Jr. recently returned from the 15-day injured list and had been one of Counsell's go-to options in high-pressure situations before suffering a forearm strain.

With Little's injury, the Cubs are left with only one left-handed pitcher in their bullpen, Drew Smyly. However, as witnessed on Friday night, Counsell may rely on Leiter Jr. to face left-handed batters when necessary.

To fill the void left by Little, the Cubs have a few options available in their minor league system. Right-handed pitchers Ethan Roberts, Michael Arias, and Daniel Palencia, all on the 40-man roster, could be called upon for Saturday's doubleheader. These options await in Triple-A Iowa. Additionally, Julian Merryweather and Caleb Kilian are currently on rehab assignments with Iowa but are not expected to return before the All-Star break.

The Cubs will now have to navigate through a challenging series without the contributions of Luke Little, who was instrumental in their recent success out of the bullpen. His absence leaves a void, but the team remains hopeful for his quick recovery and return to action.