 in Thailand, Friedrich joined Borussia Dortmund on a free transfer on 20 November 2013, following injuries to fellow stoppers Mats Hummels and Neven Subotić.He made his debut for his new team three days later, playing the full 90 minutes in a 0–3 home loss to FC Bayern Munich.Friedrich scored his first goal for BVB on 8 February 2014, netting his team's third in a 5–1 away demolition of former club Werder.