On Kalimari Desert, turn left onto the second set of train tracks that you cross. Make sure you have a SUPER STAR, or this trick will not work. When you come to the tunel, hit the trigger(z) just before you enter the tunnel. Some time after you have entered the tunnel, it should tell you that you are on the next lap! Now get back off the tracks just after the tunnel, and if you were close enough, you should be in first place!