A Red Sox source told ESPNdeportes.com that the cause of the dugout disagreement was Youkilis' temper following a poor at-bat.
"It all happened because Manny complained about Youkilis' habit of throwing bats, helmets and other objects in the dugout when he has a bad at-bat, something that has become a constant practice," the source said.
"Other players have told Youkilis in the past about the situation, which makes him look selfish and that he is more worried about each at-bat than about the team. If Boston is winning easily, there's no reason to throw objects all over the dugout because of a bad at-bat.
"There was a meeting where the team let Youkilis know that many of his teammates were tired of his explosive reactions for each bad plate appearance. It became very bothersome … more so when the team is winning and it's in first place. There's not much room for individualistic attitudes."