St. Louis Cardinals pitching prospect Daniel Poncedeleon underwent surgery to relieve pressure on his brain after being struck in the head by a line drive Tuesday.
Poncedeleon, 25, was struck on the right side of the head and was carried off the field during the Memphis Redbirds' game at the Iowa Cubs.
"We're just praying for that to go well," said Cardinals manager Mike Matheny prior to Wednesday's game at Miami. "He's still not great. There's still a lot of uncertainty as to how that's going to progress. I don't have all the technical terms for you.
"Very serious."
The right-hander was promoted to Triple-A Memphis on April 10, and was among the club's most productive starters, going 2-0 with a 2.17 ERA over 29 innings. Poncedeleon posted a 3.52 ERA with 122 strikeouts in 151 innings last season for Double-A Springfield.