The British number two took the first set but Germany's Kerber, ranked 16 in the world, fought back to win 4-6 6-3 6-3.

Keothavong had seen off Hungarian qualifier Melinda Czink in the first round in Denmark.

But after an impressive start against Kerber, she was soon pegged back by the 24-year-old, who won her maiden WTA event at the Open GDF Suez in Paris earlier this year.

Kerber will now face compatriot Mona Barthel in the next round.