The Vikings next preseason matchup is against the Steelers at the Metrodome this Saturday.  Coach Brad Childress still has not named a starting quarterback after Tarvaris Jackson suffered a sprained MCL in his right knee.  Jackson was on the field for stretching exercises yesterday.  Wide Receiver Sidney Rice missed his third straight day of practice because of a virus.  It is not known if he will take part in today’s activities.  Meanwhile, defensive end Brian Robison hopes to return to practice next week after having surgery to repair a varicose vein in his leg.