Spoiler warning: This post contains major plot details for Avengers: Infinity War, so proceed with caution. For more on Infinity War, here’s what happened to the Infinity Gauntlet at the end.
Apparently, even the Hulk has performance issues from time to time. After proving himself the undisputed champion of butt-kicking on Sakaar in Thor: Ragnarok (with a little help from the obedience disk embedded in Thor’s neck), Hulk gets a bit of an attitude adjustment in the opening act of Avengers: Infinity War after being soundly defeated in hand-to-hand combat by Thanos; the Mad Titan not only knocks Hulk unconscious, he also draws blood. Thor put up a good fight when he faced Hulk in the Grandmaster’s Contest of Champions (and certainly might’ve done plenty of damage to his “friend from work” with those lightning strikes if the Grandmaster hadn’t intervened), but this is a beating unlike anything the Hulk has faced before, and it’s clear that Thanos laying the smack down on him is enough to shake the Green Goliath’s confidence in a major way.