Uh-Oh! Nelson Mandela’s daughter is about to be forking over some serious cash!!

Zindziswa Mandela has been ordered by a judge to pay a Los Angeles boxing promoter $7.5 million for hiring him to organize a Pacquiao/Mayweather fight that never saw the light of day.

According to TMZ:

A guy named Duane Moody sued Nelson’s daughter Zindziswa Mandela for $7.5 million earlier this year — claiming she hired him to organize a Pacquiao/Mayweather bout for her father’s birthday … but ultimately flaked on the deal … and the fight never materialized.

The fight was expected to rake in $100 million — and Duane claims Zindziswa promised to pay him a 15% commission on all proceeds … but fell off the radar as he was trying to organize the match.

According to the legal docs, obtained by TMZ, Zindziswa never responded to Duane’s complaint — so an L.A. judge entered a default judgment, awarding the promoter $7.5 million in damages … plus costs.

Duane’s lawyer tells us, “We haven’t heard anything from any representative for Ms. Mandela. It appears she feels hiding in South Africa means she can avoid her obligations in the U.S.”

A rep for Zindziswa tells us her lawyers plan to challenge the judgment.

Now that’s a lot of money … but we’re pretty sure she can take care of it!