MOSCOW — Nike and other sponsors swiftly distanced themselves from Maria Sharapova on Tuesday after the world’s highest-earning female athlete outed herself as a longtime user of a recently banned drug.

Swiss watch brand Tag Heuer and German luxury car company Porsche quickly followed the sportwear giant, suspending their support of the five-time Grand Slam winner after she announced on Monday that she took meldonium at the Australian Open in January, days after the substance was banned.

Many other athletes have attacked the messenger, challenged the results or blamed others after being confronted privately by positive tests for banned drugs. Sharapova went public instead, taking full responsibility and effectively throwing herself at the mercy of the International Tennis Federation.

“I know that with this, I face consequences,” Sharapova said, waving away a question that invited her to blame her doctor or someone else on her team.

The former world No. 1 could face a lengthy ban, possibly ending her season and preventing her from competing for Russia at the Olympics in Rio de Janeiro.

Much more costly would be losing the advertising revenue that has made her the top earning female athlete for 11 straight years, according to Forbes.

“We have decided to suspend our relationship with Maria while the investigation continues,” Nike said in a statement. TAG Heuer said it has abandoned talks on renewing its sponsorship, which expired in December, “in view of the current situation.” Porsche said it has “chosen to postpone planned activities” with Sharapova “until further details are released and we can analyze the situation.” And Evian, the water company, said it “will follow closely the development of the investigation.”

Industry veterans were surprised by how quickly these companies backed away from such a bankable performer.