ANCIENT OLYMPIA, Greece (AP) — One way or another, the flame that’s to burn at the Paris Olympics will be kindled Tuesday at the site of the ancient games in southern Greece.

Forecast cloudy skies could frustrate efforts to produce the flame in the customary fashion, when an actress dressed as an ancient Greek priestess uses the sun to ignite a silver torch.

If that doesn’t work, French organizers will get their flame from a backup that was successfully lit at a final rehearsal Monday.

In an elaborately choreographed ceremony first used in 1936, the foremost of a group of priestesses in long, pleated dresses offers a prayer to the ancient Greek sun god, Apollo. She then dips the fuel-filled torch into a parabolic mirror which focuses the sun’s rays on it, and fire spurts forth.

From the ancient stadium in Olympia, a relay of torchbearers will carry the flame more than 5,000 kilometers (3,100 miles) through Greece until the handover to Paris Games organizers in Athens on April 26.