Warning: contains spoilers for Justice League: Last Ride #5!
While Superman may be the Justice League's strongest member, Wonder Woman just proved she's far more capable of taking down his most physically intimidating recurring villain. Justice League: Last Ride #5, by Chip Zdarsky and Miguel Mendonca, shows the team's final mission in an uncomfortably close potential future. While Superman and Flash deal with a Brainiac-controlled Cyborg Superman, Wonder Woman and John Stewart deal with Mongul in space. When the ruler of Warworld lets the two heroes know he won't be disbanding his armada, they have a two-on-one fight, and Diana shows she's ruthless enough to defeat a foe who often tests Superman to his limits.
In Mongul's first appearance, DC Comics Presents #27 and #28, by Len Wein and Jim Starlin, he kidnaps three Daily Planet staff members: Lois Lane, Jimmy Olsen, and Steve Lombard. Superman and Supergirl eventually find Warworld and face Mongul, but the warlord actually overpowers Superman in every encounter. It's only after Supergirl flies through Warworld, critically damaging it, that Mongul evacuates while no one is watching. Superman has struggled with Mongul in direct combat ever since, and the tyrant even knocked the Man of Steel unconscious as recently as 2020's Superman #19.
After battling against Mongul's armada in Justice League: Last Ride #4, Wonder Woman finally gets up close and personal in issue 5. At first, Mongul's jet pack gives him an advantage, and he lands several hits on Diana. However, Wonder Woman wins almost instantly after slicing his jet pack. She admits Mongul may be more powerful than she is, but that in this particular battleground, strength isn't the defining factor. As Wonder Woman kicks Mongul off into space, he bellows, "I'll kill you! You hear me?" Rather than engaging Mongul in a contest of pure strength like Kal-El, Diana accepts her limitations and earns an easy win.
Mongul is the villain who famously trapped Superman in a fantasy of his ideal world in Superman Annual #11's 'For the Man Who Has Everything' by Alan Moore and Dave Gibbons. While he faces Wonder Woman in direct battle in this story, it's actually Jason Todd who saves the day by dropping the hypnotic Black Mercy plant onto Mongul, trapping him in his own imaginary world. In Justice League: Last Ride #5, it's clear Wonder Woman learned from this battle in a way Superman never really has, resolving to beat Mongul with brains rather than brawn.
Mongul may have an incredibly high level of strength and durability, but he is not the brightest alien emperor out there. While he's relied on stratagems to combat the Justice League before, he lives by a philosophy of might making right - each Mongul is replaced by one of his children once they grow strong enough to kill him - and so Superman's regular tactic of hitting him as hard as possible is thoroughly in line with what he expects and is ready to combat. As a long-lived warrior, it's no surprise Wonder Woman is able to short-circuit Mongul's expectations with a ruthless workaround. The next time one of his more powerful enemies threatens the planet, Superman might be better off calling Wonder Woman for some tips on how to handle it.