Williams is not going to let George Russell flee to the Mercedes works team without a fight.
"We are very happy with their development. The aim is to make them ready for a seat in a Mercedes," he said.
But Claire Williams, who has Russell at the struggling British team this year on loan from Mercedes, says Williams is not going to let the 21-year-old go.
"I told Toto that George is on a three-year contract with us, he is firmly in our plans for the future and is going nowhere," she told the Daily Mail.