What you would do in a situation where your manager tells you to do "A" and your team lead tells you to do "B".
A and B are solutions to the same problem that we are trying to solve. Lead says the manager is wrong and Manager says they are correct.

Sit them both down, and refuse to work until they agree with each other. Or... agree with the one that has more power to fire you.

Alternatively, use this as an opportunity to pit them against each other sparking a feud that slowly weakens them both until you are finally given the chance to usurp their positions.

@hackedranger bahahaha

Generate a benchmark report and send it to both of them.

Sit them both down and let them hash it out. If they refuse, don't work on it.

Or: ignore them both and build it the right way.

THUNDERDOME! THUNDERDOME!

Explain politely that they are putting you in an impossible position and that you will not be doing anything until you get a clear, agreed instruction. Their difference of opinion is their problem, not yours and if they can't be made to understand that then neither of them should be in any kind of management position.

@teadrinker that's kinda what I did. This is for a spike actually. So I'm including all the ideas in a document mentioning their pros and cons. We can then decide on a collective solution. I hope.