An employee was driving a telehandler (forklift) on a rural road with drainage ditches on both sides of the road. A tube of grease rolled near the operating pedals of the telehandler and when the operator bent over to grab the tube, the telehandler veered off the road. The tires of the telehandler slid on wet grass and went into a ditch. When the telehandler got to the bottom of the ditch (approximately 15 feet below), it tipped over onto the cab's passenger side. The employee was wearing a seatbelt and struck the interior structure of the telehandler cab and sustained a fractured right clavicle requiring hospitalization.