Nike's multi-million dollar Olympics advertising campaign is in jeopardy.
Marion Jones, the record-breaking American athlete accused of taking performance-enhancing drugs, is in danger of being barred from the competition. She is under scrutiny by the US Anti-Doping Agency.
Jones is paid $3m (£1.64m) a year to endorse Nike (from a total endorsement budget which now stands at an obscene $1.36bn a year).
But Nike has a record of standing by athletes involved in doping scandals.
In 1992 when Germany's Katrin Krabbe, the world 100 and 200 metres champion, tested positive for steroids Nike continued to support her financially before she was eventually banned for four years.
In 1997 Mary Slaney tested positive for testosterone and Nike continued to back her despite the fact she was banned and stripped of the silver medal she had won in the 1500m at the world indoor championships.
Nike also stood by the Manchester United defender Rio Ferdinand after he was banned for eight months when he failed to turn up for a random out-of-competition test. He was in the first 12 months of a three-year deal with Nike worth a reported £270,000 per year.