that just goes to show why gaara is the commander general of the entire army. first he was able to defeat his father, the previous kazekage. Then while battling against this second and stronger opponent, he used the remnants of his previous fight to win the battle. He was able to make use of the gold dust left behind from fighting his father. And the fact that he saved all the other ninja with that sand shield while doing so was just an added bonus to how strong gaara is.