In the opening scene of Avengers: Infinity War, fans got an immediate taste of Thanos' skill in combat when he took on the Hulk aboard the Asgardian refugee ship. However, it wasn't much of a fight as the Mad Titan, after getting sucker-punched, made easy work of the Green Goliath, pummeling him with well-timed punches, a knee to the head and a body slam to the ground.
His beating was so bad, the Hulk refused to come out for the rest of the film, leaving us assuming he was afraid of Thanos. While the Russo brothers disputed this, saying it was because he was tired of mopping up Banner's mess, Hulk fans chalked the beatdown down to Thanos using the Power Stone, which he already acquired after ravaging Xandar. However, looking closely at the scene in the film, Thanos wasn't using it and the Russos confirmed as much. Now, though, the Avengers 4 prelude comic seems to contradict that by showing the villain was indeed using the Infinity Stone against the Avenger.
As you can see in the brawl, Thanos is having fun, as Ebony Maw so succinctly put it, with strategically placed blows incapacitating the Jade Giant. He isn't using the Power Stone, which would be glowing purple if he was harnessing its abilities and levelling his strength up for the melee. It comes down to his mental fortitude and experience as a cosmic conqueror, as the Russo brothers admitted in a Collider interview regarding the one-on-one between the two behemoths.
"I would say that he’s [Thanos] just that powerful. You didn’t see him actively use the Power Stone in that fight," said Joe Russo. "I think ultimately, the way we looked at that fight and the way talked about it with our stunt team when we were executing it was Hulk is obviously very powerful, but he’s a little mindless in his fighting style. It’s aggressive, it’s pummeling."
"Thanos is the Ghengis Kahn of the universe, he’s a very skilled fighter, equally as strong. So when you put those two up against each other, the more skilled fighter is going to win ultimately. Which is why Hulk has a moment where he overpowers Thanos, but ultimately Thanos is smart," he concluded.
In the comic, however, the artwork by Paco Diaz, contradicts this sequence. When Diaz recreates the battle, we see the gem glowing in Thanos' Infinity Gauntlet, suggesting that he was using it to power up to fight Bruce Banner's alter ego. Now, it could be a case of editorial oversight, because just before this, Thanos did use the Power Stone to torture Thor by placing his Gauntlet against the Odinson's skull, all to convince Loki to hand over the Tesseract.
In the first page of the comic, this torture scene is recreated as well, so it seems colorist Dono Sanchez-Almara merely carried on with the shining Power Stone throughout the entire opening of the story, thus, giving the impression Thanos kept harnessing its power when Hulk ambushed him.
But as the directors indicated, Thanos didn't need the artifact on the big screen; he was already at the Hulk's power level, even if this comic mistakenly hinted otherwise. It seems like an honest accident, but for now, we're sure Hulk fans will stick by what it proposes, believing that no matter what, he's still the strongest there is in the Marvel Cinematic Universe.