Toro Rosso has ruled Stoffel Vandoorne out of the running for a 2019 seat.
Belgian Vandoorne admits his hopes of keeping his F1 dream alive following his McLaren axe are close to "zero".
Red Bull has now ruled him out of the running for the second seat at Toro Rosso.
"We will not take Stoffel," Dr Helmut Marko told the broadcaster RTBF. "I think he’s just not fast enough for F1."
It seems almost set in stone that Vandoorne will instead leave F1 altogether and join the new works Mercedes team in Formula E.
"I have always liked Stoffel, a brilliant driver in the junior categories," said Toto Wolff.
"We must now try to understand why it did not work for him in F1, but maybe there could be some news about him soon.
"I think his character and speed would work very well at Mercedes, but for now we will have to see," the Mercedes chief added.