Uppercut requires being close and having the punching hand low. Inherent danger there.
Hooking range is uppercut range
Canelo throws right hook, left uppercut. This gets his range right. There's a moment where you're exposed in range but the hook keeps the opponent busy.
When pressing together in the high guard, push both their gloves with one arm (i.e. frame). This allows you to sneak the other one away and uppercut.
Hook to their ribs. When they defend this, they leave the centreline exposed to uppercuts. Do it fast.