Rub corn flour into the stain and leave for 20 minutes to draw out oils. Brush off with a cloth or brush and examine. This may require several applications to draw the oils out completely. Pretreating the stain with a small amount of dish liquid will also help remove the stain.
Run fabric, inside out, under cold water to flush out as much of the ketchup as possible. Apply liquid laundry detergent to stained area and let it soak in cold water for 30 minutes. Rinse with cold water and sponge the affected area with white vinegar. Finally, pretreat the stain and launder the item on the hottest water allowed by the fabric.
Spoon the excess off as fast as you can. Sprinkle the area with artificial sweetener or flour over the stained area to absorb the grease. Soak in a mixture of mild detergent and lukewarm water for at least 20 minutes.