Nike has said it is "deeply concerned by the disturbing allegations" facing footballer Cristiano Ronaldo.
The statement from the US sportswear firm's media department on Thursday comes after a woman filed a lawsuit in Las Vegas alleging she was raped by Ronaldo in 2009.
The Portuguese player has denied the claims.
In the email, Nike said: "We are deeply concerned by the disturbing allegations and will continue to closely monitor the situation."
Nike has had a contract with Ronaldo, one of the wealthiest and most famous footballers in the world, since 2003.
The latest terms signed in 2016 are worth a reported one billion dollars and Ronaldo has suggested it was a deal "for life".
The five-time world player of the year wears Nike boots and appears in its advertising.
The Portugal captain is also the face of the EA Sports' Fifa video game franchise, appearing on the cover of the 2019 game released worldwide last week.
"We have seen the concerning report that details allegations against Cristiano Ronaldo," EA Sports said.
"We are closely monitoring the situation, as we expect cover athletes and ambassadors to conduct themselves in a manner that is consistent with EA's values."
Ronaldo's club Juventus also released a statement via Twitter, which read: "The events allegedly dating back to almost 10 years ago do not change this opinion, which is shared by anyone who has come into contact with this great champion.
"Ronaldo has shown in recent months his great professionalism and dedication, which is appreciated by everyone at Juventus."
Ronaldo has been left out of Portugal's national team squad for matches against Poland and Scotland.
The Portuguese national team's Twitter account quoted manager Fernando Santos as saying: "In the future, nothing prevents Cristiano from giving his contribution to the national team."
The Juventus player is at the centre of an allegation that he raped an American woman nine years ago in a Las Vegas hotel.
Lawyers for the accuser, Kathryn Mayorga, said on Wednesday their client has been diagnosed with post-traumatic stress and depression.
Earlier this week, the 33-year-old Portuguese player used social media to label the allegation “fake news”.
He took to Twitter on Wednesday evening to again deny the accusation.
A civil lawsuit filed on September 27 in state court in Las Vegas alleges Ronaldo raped Ms Mayorga in his penthouse suite at a Las Vegas hotel and hired a team of what the document called “fixers” to pressure Ms Mayorga to keep quiet.
Las Vegas police said they would not be releasing the report that Ms Mayorga filed the day she said she was attacked, because the investigation is open.