On 4 July 2013, it was revealed that Berg had travelled to Athens in order to sign with Panathinaikos. On 8 July 2013, Panathinaikos announced that Berg had signed a four-year contract with the club. On 18 August 2013, in his debut appearance, Berg scored his first goal with Panathinaikos, as his team won the game against Panetolikos. On the first derby of the year against PAOK, Berg scored Panathinaikos' goal and lost a penalty, as his team lost with a score of 2–1. On 2 March 2014, Berg was the MVP in the 3–0 away victory against Olympiacos with one goal and one assist for Danijel Pranjić. This was the biggest away victory in the history of the Eternal Rivals. The following week, he scored a hat-trick when Panathinaikos defeated Aris 4–1 at home.