GCN Mario Circuit is the 4th track of the Leaf Cup.The circuit surrounds the Castle of Princess Peach, while in the background some Warp Pipes, tall toadstools, smiling trees, and a Mushroom-shaped hot-air balloon midair can be seen, overviewing the track. A giant Chain Chomp guards a piece of rough terrain, ramming into any vehicle who passes near to it. Also, some Piranha Plants appear, attacking the karts and bikes that pass too close to them, causing the racers to roll over and drop their items onto the road. However, they are vulnerable to being hit by some items, such as Green Shells, which leave them stunned for a while. Another obstacle are the Goombas crossing the track back and forth, before the finish line. Making contact with one causes the kart to spin around. By using certain items against these enemies, a Mushroom pops out of them.The course contains many curves and corners. Employing drifting is the main hint given to clear this circuit. After the first turn and another tight turn, the racers will encounter the Chain Chomp wandering the zone, biting the trespassers. Players then enter a curved tunnel, crossing a bridge upon leaving it and discovering a soil road. After getting into another corner, racers face Goombas crossing an uneven road, giving the racer certain difficulty to maneuver well. After crossing another bridge (where two Piranha Plants await racers to attack indiscriminately), the racers reach the finish line and the lap is completed.