The Boston Red Sox have added a rising slugger to the injured list due to a toxic concussion.

Boston Red Sox outfielder Tyler O’Neill will be out for at least the rest of the week after sustaining a concussion in a collision with teammate Rafael Devers during Monday’s game against the Cleveland Guardians. The team has placed him on the 7-day injured list, retroactive to April 16.

The collision, which occurred on Monday, left both players shaken up. While Devers was able to remain in the game, O’Neill exited and did not return. He received eight stitches near the top of his nose and entered the league’s concussion protocol. As a result, O’Neill was not in the lineup for the Red Sox on Tuesday or Wednesday, and he will miss at least the next four games. He will be eligible to return on April 23 when the team begins a road series against the Guardians.

To fill O’Neill’s spot on the roster, the Red Sox have reinstated outfielder Rob Refsnyder from the 10-day injured list.

O’Neill has been a standout performer for the Red Sox this season, leading the American League with a .750 slugging percentage and 1.209 OPS. He is batting .313 with seven home runs, eight RBI, and 11 walks.

Boston acquired O’Neill in a trade with the St. Louis Cardinals in December. The 28-year-old outfielder had a breakout season in 2021, hitting .286 with 34 home runs, 80 RBI, 15 stolen bases, and a .912 OPS. He won Gold Glove Awards in both 2020 and 2021. However, he struggled over the next two seasons, hitting .229 with a .707 OPS, while dealing with injuries that caused him to miss significant playing time.

Now, O’Neill finds himself sidelined once again, albeit for a shorter period, due to his recent concussion.