First things first,you stand absolutely no chance against a lion.They are way too fast and way too aggressive.Silverback,if you let it punk you out and act as submissive,you have a shot,and bears in general are fucking idiots,so there's a decent chance that you actually could punk one out,wolverines do it all the time,though they are black bears and not grizzlies.Also,if you just play dead,they generally lose interest.
As a matter of fact,why did the OP choose grizzlies anyway?Polar bears are waaaaaaay more dangerous.
Anyway,anyone that choose lion is fucking crazy and is obviously wishing for a quick death.