10/15/2014 10:45 am ET Updated Oct 15, 2014

Jeremy Guthrie Rubs Salt In Baltimore's Wound With 'These O's Ain't Royal' Shirt

Kansas City Star via Getty Images

Kansas City Royals pitcher Jeremy Guthrie rubbed some salt in the Baltimore Orioles' wound after his team took a 3-0 series lead on Tuesday night. Following a start where he only allowed one earned run over five innings, Guthrie sat down for his postgame press conference wearing a royal blue shirt that said, "These O's Ain't Royal" (apparently a reference from a Chris Brown song).

Guthrie, who spent five seasons with the Orioles from 2007 to 2011, sparked outrage among the Baltimore fanbase on social media with his shirt. After realizing that he angered many O's fans, Guthrie apologized on Twitter.

Speaking to reporters before Game 4 on Wednesday, Guthrie expanded on his apology.

"I have very good friends on the Orioles," Guthrie said, via USA Today Sports. "Those who said, 'well, I thought that was pretty low, a low blow or inappropriate.' I apologized and they accepted."