The 28-year-old Petkovic (pictured above) came back after failing to win a single game in her first set against Monica Niclulescu in Cluj-Napoca on Sunday, and won the match 0-6, 7-6 (7/1), 6-3 to give Germany an unassailable 3-1 lead in their relegation playoff against Romania. Germany would go onto win the playoff 4-1, meaning they will play in the top tier of the Fed Cup in 2017.

"With these emotions and the support of this team, anything is possible," said Petkovic, who was forced to battle back from two match points to win the match, which lasted just over two and a half hours.

It was the second grueling match in the space of 24 hours for Petkovic, after she had been defeated by Simona Halep in just under three hours on Saturday.

Angelique Kerber had put the Germans up 2-1 earlier on Sunday, when she beat Halep 6-2, 6-2.

"I have found my rhythm again and I am almost at 100 percent," said Kerber, who had suffered a dip in form since winning the Australian Open in January.

Annika Beck and Julia Goerges then finished the job on Sunday, with a 6-7(5/7), 7-6(7/4), 10-7 win over Irina-Camelia Begu and Alexandra Dulgheru in the dead doubles rubber.

Germany had been forced into the relegation playoff after losing 3-2 at home to Switzerland in February.

Romania are now relegated to World Group II.

Czech Republic to face France in finals

Meanwhile, the Czech Republic are to face France in the finals of the Fed Cup, after they defeated Switzerland 3-2 in their semifinal against on Sunday. Earlier, France, which is to host the finals in November, had advanced by beating the Netherlands 3-2 in their semifinal.

pfd/rd (AFP, dpa)