In December 2003, coach Marit Breivik made Hammerseng captain of the team, replacing fellow Gjøvik native Else-Marthe Sørlie Lybekk.

After a serious knee injury kept her out of the court in the 2005/06 season, Gro Hammerseng repeated her 2004 success at the 2006 European Championship in Sweden.

[9] At the 2007 World Championship, Norway was defeated by Russia in the final match, marking the third silver medal for Hammerseng.

The 2008 Summer Olympics gave the Norwegians an opportunity for revenge, as they met Russia in the final match.

[12] 2004 2005 2006 2007 2008 2009 2010 2023 Hammerseng was in a long-term cohabiting relationship with fellow Larvik HK and Norwegian national team player Katja Nyberg.

[18] In the lead-up to the 2008 Beijing Summer Olympics, Hammerseng joined other Norwegian athletes in an Amnesty International campaign for human rights in the People's Republic of China.