Former F1 driver Timo Glock says he feels for Sebastian Vettel.

Although delaying Lewis Hamilton's 2018 title win for now, German Vettel's campaign nonetheless continued to fall apart in Austin as he spun early in the race in a clash with Daniel Ricciardo.

"This is the third time," the Ferrari driver told the German broadcaster RTL.

"It should not be this way, especially because we should have taken better advantage of the weaknesses of Mercedes."

Vettel said he is at least happy for his teammate Kimi Raikkonen, who ended a long winning drought.

"It was a tough week for the team. Only for me does the hard time seem to be not over," he explained.

Glock, now a pundit for German television, says that amid continuing criticism of Vettel, he feels for the quadruple world champion.

"You can see that it hurts him. I know him and I've rarely seen him like that," he said.

"He needs to find the reset and start again. The small mistakes must stop. The fact that Ferrari is back on Mercedes' level must at least give him a boost."