Many comic fans know this issue because of "The Punch". Comic Book Resources rated this "fight" #16 on its list of "25 Best Comic Battles".
Here is their write up:
The Justice League of America fell apart during the mid-80s, when most of the members of the team were killed by an old nemesis of the League, Professor Ivo. After the crossover “Legends,” a brand new Justice League was formed, made up of mostly superheroes that had never been in the League before, such as Mister Miracle, Captain Marvel, Blue Beetle and Doctor Fate, along with old League stalwarts such as Martian Manhunter, Batman and Black Canary. One new member had a certain idea of how he was going to be involved with the team, and that member was Guy Gardner, a member of the Green Lantern Corps. He felt that he should be the leader of the team.
In the very first page of “Justice League” #1, by writers Keith Giffen and J.M. DeMatteis and artist Kevin Maguire, Guy is shown waiting for the rest of the members of the new League. He is dismayed, though, when he discovers that the rest of the team tends to look to Batman for leadership.
Over the next few issues, the other Leaguers soon grew tired of Gardner's constant complaining, but they also did not appreciate Batman's churlish handling of leading, either. He could have dealt with Gardner in many different ways – he chose to treat Guy like a child, only enraging Guy even more.
The relationship came to a head in quite a humorous fashion in “Justice League” #5, when Guy decides to finally decide once and for all who is in charge. In the issue, he challenges Batman to a fist fight.
Batman agrees, and after Guy takes a swing, Batman proceeds to knock Guy unconscious with one punch.
This greatly amuses Blue Beetle, and it confuses Martian Manhunter and Black Canary, who enter the room to see Guy out cold on the floor.
Beetle's repeated "One punch! One punch!" has become a catch phrase forever associated with Giffen and DeMatteis' Justice League.