German Eurovision fans had been worried that Wahl's illness would prevent the girl band from competing in Belgrade on Saturday. But their fears were laid to rest on Thursday after Wahls was given a clean bill of health on Thursday by a doctor.
The three other members German group tried to put their troubles behind them by going on a boat tour of the Serbian capital while Wahls rested.
The band - cast out of a television talent show in 2000 - will perform their song "Disappear" at Saturday's contest.
Together with the other three major contributers to the European Broadcasting Union - France, the United Kingdom and Spain - and host country Serbia, the German group was allowed to skip the contest's semi-finals on Tuesday and Thursday and head straight for competition with 24 other countries in the finals on Saturday.
A few hundred metres from the German quartet's hotel, media from around the world were already gathered at the Belgrade Arena - though there was little speculation among the press corps that No Angels would win the trophy. Online betting firm Paddy Power on Thursday put Germany's chances of winning at 100 to 1, in the lowest third of competitors. Oddsmakers ranked Russia highest, with three-to-one chances of winning.
Some fans said there was also little sign in Belgrade of the obsession that met Eurovision at its recent outings in Helsinki and Kiev. Looting in the city after Kosovar independence was declared in February left some observers concerned about the city's ability to host the contest.
Indeed, few banners for Europe's biggest television event were visible along the banks of the Save and Donau rivers. German press agency DPA reported and Tuesday night's semifinal saw numerous empty seats in the 20,000-capacity Belgrade Arena.
But Eurovision expert Irving Wolther, of the Hanover College for Music and Theatre, told DPA that Belgrade had risen to the occasion.
"The event is perfectly organized. I have also experienced only positive reactions from residents," Wolther said.
Wolther said the musical quality of this year's contest is high, with more singers from Eastern European countries - a powerhouse in recent years in the contest - venturing songs in their native languages.
Germany last won Eurovision in 1982, when blue-eyed 17-year-old Nicole Hohloch took top honours with her German-language ballad "A Little Peace," or "Ein bisschen Frieden".