Tag Heuer was in talks to extend its deal with Miss Sharapova, which ran out at the end of last year but in a statement seen by CNBC Tuesday, the company said it will not now renew the contract.
Porsche, meanwhile, has decided to postpone "planned activities" with Sharapova. The German automaker says it wants to analyze further details.
Sharapova is recognized as the world's highest-paid female athlete, earning $29.7 million dollars in prize money and endorsements between June 2014 and 2015, according to Forbes.
The player also enjoys deals with the likes of American Express and Evian.
Sponsors have moved more quickly to disassociate themselves with athletes since some got "burned" by sticking by Lance Armstrong and others during scandals, said Manish Tripathi, an Emory University marketing professor who studies sports. Swift social media spillover has also made companies react more quickly, he added.
Sharapova's recent stretch of injuries and poor performance makes sponsors' decisions easier, Tripathi noted.
"It was easier for Nike and others to cut ties because she has been completely overshadowed recently by other players such as Serena Williams. It makes more sense to potentially bet on other upcoming stars or invest more in stars like Serena," he said.
CNBC takes a look at some of the other high profile athletes that have that lost sponsorship.