Cubs starting pitcher Justin Steele left his Opening Day start early on Thursday after fielding a bunt and falling as he flipped the ball to first base.

He seemed to be holding his left hamstring as he walked off the field, per Sahadev Sharma of The Athletic. The team later confirmed to reporters (including Sharma) that Steele exited the game with left hamstring tightness.

After the game, a 4-3 loss to the Rangers in extra innings, Cubs manager Craig Counsell used the word “strain” to describe Steele’s injury (per Sharma). He added that the All-Star left-hander will likely go on the injured list, but as Meghan Montemurro of the Chicago Tribune notes, the skipper would not speculate about how much time Steele could miss.

The southpaw will undergo an MRI on Friday (per Montemurro), after which the team will likely have a better idea about the severity of his injury and how long he might spend on the IL.

Counsell told reporters, including Maddie Lee of the Chicago Sun-Times, that the team does not yet have a plan for who will take Steele’s spot in the rotation. Left-hander Drew Smyly and right-hander Hayden Wesneski seem to be the most likely candidates, given their presence on the 40-man roster and recent experience pitching out of the big league rotation.

Smyly, 34, made 23 starts for the Cubs last year, while Wesneski, 26, made 11. However, Smyly found success in a bullpen role down the stretch in 2023; he made some starts this spring but was largely preparing to start the season as a reliever.

Meanwhile, Wesneski struggled tremendously as a starter last year (5.51 ERA, 6.26 FIP) and looked even worse in six outings (four starts) this spring.

Ben Brown, 24, is one more name on the 40-man roster to keep an eye on. He transitioned to a bullpen role last season, but he has recent starting experience and looked sharper than either Smyly or Wesneski this spring.

What’s more, his move to the bullpen may have simply been a way to accelerate his path to the major leagues, not a permanent change. He was quite good in 19 minor league starts last season, pitching to a 3.81 ERA and racking up 120 strikeouts in only 85 innings pitched.

However, his lack of experience may work against him; Brown has yet to make his MLB debut.

Whether it is Smyly, Wesneski, Brown, or another arm entirely, the Cubs have a difficult decision to make before what would have been Steele’s next turn in the rotation: the final game of the home opener series against the Rockies on April 3.