Again, this is all up in the air, so the details could be different; Goku could end up fighting Jiren alone, with a fully unlocked UI vs. Jiren’s full power, which is bigger than that of a God ...

Goku is not even close to mastering his new power-up, and the hero has yet to beat Beerus full-on in a match. If Jiren is said to be equal or superior to the God of Destruction, then Goku is going ...