* Frivolity over after she joins World Cup victory party
* “Mutti” to Germans, world’s most powerful woman to Forbes
* Media speculation about how long she will stay chancellor
* Physicist from old Communist East Germany rose to top
* No-nonsense approach helps appeal, World Cup win a plus
By Madeline Chambers
BERLIN, July 16 (Reuters) - Angela Merkel, it seems, has had her fill of parties for now.
Just four days after joining Germany’s jubilant soccer players in their dressing room to revel in their World Cup triumph, the chancellor is making sure she doesn’t get carried away on her 60th birthday on Thursday.
It is hard to imagine a more low-key celebration for Merkel, named by Forbes magazine as the world’s most powerful woman but still known as “Mutti”, or Mummy, in her homeland where her no-nonsense attitude merely enhances her soaring popularity.
She will mark the birthday, which has set off a new debate about how long Germany’s first female government leader will stay in office, at a rather serious event at her conservative party’s headquarters in Berlin.
After a speech about “the time horizons of history” by the historian Juergen Osterhammel - Merkel’s personal choice - up to 1,000 guests will attend a reception with beer, wine and northern German fare including fish.
Nothing too fancy, said one official.
She may even see in her birthday in Brussels where European Union leaders meet late on Wednesday to haggle over how to carve up posts in the European Commission between member states - just the sort of challenge Merkel relishes.
After a tough start to the year, which saw her hobbling on crutches after a skiing accident, a crisis in Ukraine to deal with and her Social Democrat (SPD) coalition partners stealing the limelight on domestic policies, she looks as strong as ever.
A Forsa poll on Wednesday showed that even after 8-1/2 years as chancellor, some 59 percent of Germans would vote for Merkel in a head-to-head contest with her main rival, SPD chairman Sigmar Gabriel. Only 14 percent would vote for him.
An Infratest dimap poll on July 3 found that 71 percent of Germans were happy or very happy with her work. Germany’s strong, well-managed economy within an otherwise troubled euro zone has helped her. Forsa chief Manfred Guellner said the World Cup victory could play in her favour as well.
“The chancellor stage-managed it skilfully as she went to Brazil for the first match and then for the final. The message was: I am paying it attention!” Her ratings are so high there is barely room for improvement, he said.
The inscrutable physicist who grew up in Communist East Germany and fought her way through a male party hierarchy shows no sign of giving up. The Forsa poll showed that 26 percent of Germans want Merkel to stay in office for another decade.
She relaxes by hiking in the Alps, listening to Wagner operas and cooking simple meals for her publicity-shy husband Joachim Sauer, a quantum chemist. They do not have children.
After losing 10 kilograms (22 pounds) this year, Merkel told German television on Sunday that she wished just for good health on her 60th birthday.
Asked if she aimed to outdo her former mentor Helmut Kohl’s tenure as chancellor from 1982-1998, Merkel said she wanted to serve her full term in an orderly fashion. Then she would see.
German media have long speculated that she does not want to stand for a fourth term in 2017, and they link her to top European and international jobs. In the television interview she was asked about becoming U.N. Secretary General in 2018.
“That will certainly not happen,” was her blunt response.
Merkel has been widely reported as telling photographer Herlinde Koelbl back in 1998 that she wanted to quit politics at the right time, saying: “I don’t want to be a half-dead wreck.” (Editing by Mark Heinrich)