<span class=normal>By now its common knowledge that the shooting of YRFs eagerly anticipated flick Dhoom 3 is on in full swing in Chicago. Recently, the Dhoom boys had a surprise visitor on sets and it was none other than Amitabh Bachchan who took some time off from his hectic schedule to meet up with his son Abhishek and the rest of the Dhoom 3 gang. </span>