The Rockets (3-0) led 15-14 after one quarter, but Colin Swain's three-pointer highlighted a 6-0 Greencastle run to start the second. Scott Bell hit a turnaround jumper for Buchanan to break the string. After a Greencastle free throw, the Rockets strung together six straight to take a 23-21 lead.
Three consecutive turnovers and an offensive foul by Greencastle (0-1) helped the Rockets build a 30-23 lead just 90 seconds into the second half. The first of five three-pointers by Derek Heckman capped the 7-0 run.
Another trey by Heckman pushed the lead to nine at 40-31. Two baseline jumpers by Dan Thrush, who finished with 10 points, cut the deficit to six with three minutes left in the third.
More Greencastle turnovers in the fourth quarter turned into points for Buchanan. Heckman's fourth three-pointer came in the middle of a 7-0 run that extended the Rockets' cushion to 56-40.
Five straight points by Dallas Strait ended the Blue Devils' scoring drought, but Heckman drained another three to steal back any momentum Greencastle may have gained.
"They made adjustments in the second half, changed up the defense and took advantage of a couple of letdowns by us," said Greencastle coach Mike Hussack. "They started hitting the threes and got a few calls and the momentum shifted."
Colin Swain led Greencastle with 20 points and Dave Schnabel had 10 rebounds. For James Buchanan, Justin Dovey had 14 points and 12 rebounds, and Troy Gipe had 13 points and 10 assists.