CBS Sports and Turner Sports scored last night. Their first-round coverage of the 2013 NCAA men’s basketball tournament on CBS, TBS, TNT and truTV averaged an overnight household rating/share of 5.8/14. That’s the highest first Thursday ratings of the tournament since 1991. It is also up 4% compared with the 5.6/13 that the tournament received on the comparable night of March 15th last year. This is the third year CBS and Turner are showing all 67 March Madness games across four networks. The first primetime slot (7-10:15 PM), which saw South Dakota State vs. Michigan on CBS, averaged a 7.4/14 to register the highest rating ever for the time slot and was up 9% over the 6.8/13 the first primetime game of the night got in 2012. The second primetime slot of the night (9:30 PM – 12:45 AM) averaged a 6.4/11, down from the 6.8/12 of 2012, but featured two blowouts: Virginia Commonwealth thrashing Akron by 46 points on CBS and Syracuse slamming Montana by 47 on TNT. So far, this year’s March Madness, which began Tuesday with the NCAA First Four, is averaging a 5.2/12, up 2% compared with a 5.1/12 at the same time last year.