BERLIN (AP) — Former tennis star Boris Becker says it's time to stand up against racism amid a controversy over a slur directed at his son from the Twitter account of a German nationalist lawmaker.

In an article for Sunday's Welt am Sonntag newspaper, Becker questioned the assertion of Alternative for Germany lawmaker Jens Maier that the tweet about Noah Becker was posted by a member of his staff. He called for "consequences."

A lawyer for Noah Becker said Thursday the 23-year-old had filed a criminal complaint against Maier, who has said he regretted the "mishap."

The elder Becker wrote in Sunday's article that racism must no longer be accepted and "it is time to stand up ... here and all over the world."