Mercedes' Norbert Haug has laughed off reports that Nico Rosberg could be set to switch to Ferrari.
Italian magazine Autosprint reported that Ferrari made initial "contact" with German Rosberg recently about racing alongside Fernando Alonso next year.
Bild newspaper said it believes that, depending on his results at Mercedes this season, the 25-year-old could get out of his contract at the end of 2011.
The German marque's motor sport chief Haug responded: "Last weekend it was the first of May, not the first of April. So this joke is a month too late."
Bild said Rosberg would not comment on the Ferrari reports.
But he told the newspaper's Sunday edition after Shanghai that he would have no qualms lining up in a team alongside the likes of Alonso, Lewis Hamilton or Sebastian Vettel.
"They are all top drivers and I would take on any of them," he said, then referring to Michael Schumacher: "I already have the best driver of all time in my team."
And Rosberg told the DAPD news agency: "I am very happy where I am, I believe in the team and want to go with them to the top."