Groupon Challenges GrubHub and Yelp With 10% Off All Delivered Orders

Service debuts in Chicago with Mike Ditka, of course

Groupon officially jumped into the restaurant delivery game on Thursday, offering 10 percent off every order in Chicago from national chains such as Quiznos, Popeyes, Subway and Papa John's, as well as Windy City eateries like Ditka's, Al's Beef, Star of Siam, and Wishbone.