Andy Murray believes Maria Sharapova deserves to be suspended after the five-time Grand Slam winner admitted to failing a drugs test.
Despite his racket sponsor Head supporting the Russian, suggesting she had not intended to gain a competitive advantage by using meldonium and that she had made an 'honest' mistake, world number two Murray believes she must be banned.
The Scot said on BBC Radio Five: "On January 1st that substance was made illegal and she was taking it through January and into the Australian Open, so it was.
"The 10 years before that she was taking it, it's not on the list so there's not a whole lot you can say about that, but it became illegal and she, along with a number of other athletes who were still taking it... You have to accept responsibility for that and take the suspension."
Speaking at a press conference in Indian Wells ahead of his participation in the BNP Paribas Open, Murray continued: "It's not up to me to decide the punishment, but if you're taking performance-enhancing drugs and you fail a drugs test, you have to get suspended."
Head released a statement on Thursday claiming it was "proud" to be associated with the Russian just three days after her revelation that she had tested positive for meldonium at the Australian Open.
The company also announced the intention to extend Sharapova's contract, even though she is facing a possible four-year ban from tennis, and Murray was baffled by the approach from a sponsor he has used throughout his career.
"I think it's a strange stance, given everything that's happened the last few days," he said.
"I don't really know what else to say on that, but that's not something I believe.
"I think at this stage it's important really to get hold of the facts and let things play out, like more information coming out before making a decision to extend the contract like that, in my view. I personally wouldn't have responded like that."
Murray's comments came after Head had publicly backed Sharapova despite a number of her other sponsors, including Nike and Porsche, distancing themselves from her, while watchmaker Tag Heuer vowed to cut ties completely.
Sharapova has used Head's equipment since 2011 and a statement from chairman and chief executive Johan Eliasch read: "The honesty and courage (Sharapova) displayed in announcing and acknowledging her mistake was admirable.
"Head is proud to stand behind Maria, now and into the future and we intend to extend her contract. We look forward to working with her and to announcing new sponsorships in the weeks and months ahead.
"Maria may have made a mistake, but she has earned the benefit of the doubt and we are extending it to her."