A night earlier Paul Pierce had told his team — perhaps with an eye towards his younger and newer teammates — of the benefit a win in one of the toughest arenas for visiting teams would pay. Along with fellow oldie Kevin Garnett, Pierce then showed them why the Celtics are known for moments like this. Both players, bone tired on the last night of a five-game western road trip, combined for 11 of the Celtics’ 13 points in the clinching overtime period of a 110-107 win over Utah. It was the Celtics’ 10th overtime game of the season. They are now 6-4 in those situations. The Celtics took the lead six times, with Utah answering with a tying score each time, in the last 6:56 of regulation. Pierce, who missed on the last shot of regulation, finally broke loose when he buried a go-ahead trey with a 102-101 lead with 2:30 left in the overtime.