In the world of One Piece, Admirals represent the military might of the World Government. Over the years, fans have witnessed their overwhelming power on many occasions. Despite their strength, Admirals are often considered inferior when facing the Yonko.
This perception has been proven true. We’ve seen many Admirals confront the Yonko, but none have truly gained a decisive upper hand. However, Oda has now confirmed to fans the identity of an Admiral who can genuinely match the Yonko and even has a chance to defeat them.
It seems that every era in One Piece history has at least one Admiral who achieved this feat. In the previous era, it was Admiral Sengoku, who later became Fleet Admiral. In the current era, it is Fleet Admiral Sakazuki, also known as Akainu.
Fleet Admiral Sakazuki Is on Yonko Level

Fleet Admiral Sakazuki currently poses a threat equal to the Yonko. Under his leadership, the Navy has become more aggressive than ever, even pursuing powerful individuals and forces like the Yonko in the New World.
Regarding his personal strength, fans know Sakazuki is a monster wielding the Logia-type Magu Magu no Mi (Magma) Devil Fruit, allowing him to unleash large-scale destruction with molten lava.
Sakazuki also possesses powerful Haki, and it wouldn’t be surprising if he is later revealed to have Conqueror’s Haki. After all, the bounty Cross Guild placed on him is 5 Crowns, equivalent to 5 billion Belly, second only to Whitebeard and Roger’s bounties.
So far, Oda hasn’t shown Sakazuki in major battles, which only strengthens the belief that when he finally acts, his display of power will be terrifying. When Akainu officially enters the fray, he will prove to fans why he is a threat on par with the Yonko of One Piece.
Admiral Sengoku Earned Roger’s Respect

In the previous era, before the Great Pirate Era, Admiral Sengoku was also regarded as a legendary figure on par with the Yonko. Although this was once debated, the fact remains that Roger himself considered Sengoku a worthy opponent.
Roger’s belief that Sengoku deserved to fight him, even if he wasn’t entirely his equal, shows Sengoku was strong enough to compete with the Yonko. Even the legendary Whitebeard had a personal rivalry with Sengoku, further confirming Sengoku as a Yonko-level threat.
Moreover, Sengoku was the second Navy figure known to possess Conqueror’s Haki after Garp. In other words, Sengoku was an absolute top-tier character in the old era of One Piece, much like Akainu is today.
Other Admirals Are Still Weaker Than the Yonko

As for other Admirals in One Piece, like Kizaru, Green Bull, and Fujitora, the truth is they are weaker than Sengoku and Akainu. While they are formidable monsters in their own right, their achievements don’t compare to those two legends.
For example, Kuzan (Aokiji) admitted that even against an aging Garp, he couldn’t win without help from Blackbeard’s commanders. Admiral Green Bull was recently embarrassed by Shanks in the story. Meanwhile, Kizaru couldn’t defeat Luffy, who hasn’t even reached Yonko-level strength yet, and was easily incapacitated by him.
Admirals are definitely weaker than the Yonko, but Fleet Admirals Akainu and Sengoku are exceptions, which makes sense since both rose to the rank of Fleet Admiral.