Never doubted for a second - Tradução em português

Hi everybody,
Please, could you guys help me with this phrase?
One of the worst performances of my career and they “never doubted it for a second”.
Is “never a doubted for a second” an expression?
Or can I translate it word by word?
Could I say, in Portuguese:
They “never doubted it for a second.” = Eles ném duvidaram.
They “never doubted it for a second.” = Eles não duvidaram ném por um segundo.
They “never doubted it for a second.” = Eles nunca duvidaram disso…

So, what do you guys think, what is better? What are your tips?

Thankful.