How to upgrade a Qatar Air flight with Amex Explorer points?


I have a booked flight with Qatar from Sydney to London. Is there a way I can transfer my American Express Explorer points to a partner programme to upgrade the existing flight?
Air Asia keeps saying upgrade award is unavailable on that route.

You can only upgrade with Qatar points.

From Amex Explorer you can transfer to Starwood at a 2:1 ratio, then onwards to Qatar at a 1:1 ratio, with a 5000 mile bonus per 20,000 points transferred.

These two transfers will each take likely a few days, so I’d want to be 100% sure upgrade space was available, that your ticket is eligible for upgrade, and how many points you would need before committing. Even then it’s a risk, as the upgrade availability could change while you wait for those two successive transfers.