Germany defender Mats Hummels has admitted he was angry to hear Borussia Dortmund and national team-mate Mario Goetze had decided to leave the Champions League finalists to join Bundesliga rivals Bayern Munich.
Rising star Goetze, 21, actioned a release clause in his Dortmund contract to allow him to join Bayern for 37 million euros (US48m, £31m) and news of the transfer broke in April, just before Dortmund's Champions League semi-final win over Real Madrid.
But Hummels, 24, was bemused why Goetze wanted to join Champions League winners Bayern from a Dortmund side which won back-to-back Bundesliga titles in 2010-11 and 2011-12 and could not understand the decision.
"No, and I told him that. It surprised everyone in the (Dortmund) team," Hummels told magazine Sport Bild with Goetze now a Bayern player.
"That shows that previously it (leaving to join another club) was never a big issue. Everyone has seen how good our team is.
"I just think that there were or are little to no sporting reasons to leave us.
"You could see how our team has developed and Mario got along very well with many in the team.
"It made me so angry that he felt the need to leave so early."
Having suffered a hamstring injury in April, Goetze was unable to play in Dortmund's 2-1 defeat to Bayern Munich in May's Champions League final at Wembley.
Goetze's transfer makes him the second highest transfer in Bundesliga history behind the 40 million euros (US$52m, £34m) Bayern paid for Javi Martinez in August 2012.