It didn't take long for Flash and Green Lantern to work out whose powers were better. Within minutes of meeting one another in The Flash Annual #2, Barry and Hal found out who comes out on top when it comes to speed versus constructs.
Of all the friendships that have been forged in the Justice League, few are as strong and as close as the bond between Green Lantern and Flash. Barry and Hal have had each other's backs for years, often partnering up during missions and even hanging out outside their superhero work. And while the Flash and Green Lantern's best friendship might make them great partners, there's always the question of who would beat who if it came down to it. After all, it's hard to imagine how super speed and the overwhelming force of a Green Lantern's Power Ring would shake out in a clash.
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That being said, Barry and Hal found out where their powers stood almost instantly when they first met. In The Flash Annual #2 by Brian Buccellato and Sam Basri, the two friends are forced to recall their first mission in which an alien collective was kidnapping orphaned children. Flash does some detective work and believes he knows where the criminals are going to strike next. Unfortunately for Barry, he's not the only one working the case as Green Lantern shows up and mistakes Barry for being the perpetrator. Binding Barry in a giant jade construct, Green Lantern demands to know where the children are. Not wanting to deal with the interstellar officer's theatrics, Barry accelerates the atoms in his body and easily slips out of the Lantern's construct, completely mystifying Hal.
While it's not exactly a no-holds barred, bare knuckle brawl between the two, the moment does quickly establish that Flash's speed powers have what it takes to defeat a Green Lantern's construct. Granted, this is when Hal was still relatively new to his role as a Lantern who likely didn't account for Barry being a potential metahuman. But even if he had, this one instance proved that early into their relationship, Hal knew that Barry could easily beat him if they ever truly fought. While there's little doubt that Hal Jordan has strong willpower and makes for a great member of the Green Lantern Corps, the truth is that his powers have too many drawbacks. For one, a Green Lantern's Power Ring is limited by a hero's imagination, which isn't exactly Jordan's strong suit. Lantern rings are also reliant on remaining charged to be effective, putting a Lantern's constructs in danger if their rings run out of power. On the other hand, Flash virtually has no limits and the Speed Force is just chock-full of surprising ways to augment Barry's speed powers.
Barry and Hal's first meeting could have only ever ended one way: with the natural powers of the Flash putting the limited Green Lantern ring to shame.