Preheat a BBQ for medium heat and lightly oil grate.
In a large, nonporous bowl, combine the oil, tomato puree, wine, vinegar, garlic, salt, ground black pepper, mustard powder, celery salt and chilli powder then mix well. Pierce the roast with a fork all over the meat. Place the meat in the bowl with the marinade then turn several times to coat. Cover and marinate in the refrigerator for at least 12 hours, turning occasionally.
Barbecue over medium heat for 10 to 12 minutes per side, or until your desired doneness is reached.