BERLIN (Reuters) - German Chancellor Angela Merkel donned a pale orange blazer to work on Wednesday to Dutch delight and German disbelief, as both countries braced for their Euro 2012 soccer match in Kharkiv, Ukraine.

"Today of all days!", exclaimed German newspaper Bild on its website. "How could you?"

Dutch media reveled in Merkel's choice of their national color. "Is Merkel a secret fan of the Dutch?," asked paper NRC Handelsblad.

The two nations have enjoyed a long-standing rivalry on the pitch since the emergence of the Dutch as a global football powerhouse in the 1970s, particularly after Germany's 2-1 final victory at the 1974 World Cup.

Merkel is a fervent supporter of the German team, often seen wildly cheering in the stands, as she did during the previous European championship in 2008 in Austria and Switzerland.

She dropped in to visit the Germany team at their base in Gdansk last week and posted pictures on her website of herself sharing a meal with the team.

(Reporting by Annika Breithardt in Berlin; writing by Alexandra Hudson in Warsa; editing by Justin Palmer)