Northampton responded better to those tetchy moments and, just a couple of minutes later, scored their second try of the game, and this one proved to be the vital score.
Caleb Ralph scored a late try for the Crusaders, but the visitors were unable to breach the line again for the vital score.
Chris Riley's superb pick-up from Ryan Atkins produced the vital score before Paul Wellens grabbed a consolation.
Full-back Matthew Clarke delivered a low ball from the left, substitute Peter Thompson touched it on and Carvill pounced in front of goal for the vital score.
It meant I could look around and not worry too much about any vital score.
For the third straight match, France conceded a vital score after a turnover.
But it was such a vital score and I couldn't have lived with the humiliation if I hadn't made it.
Pienaar was then well short with a 56th-minute penalty but made no mistake with a straightforward chance on the hour mark, a vital score to settle Ulster after conceding 12 points without reply.
Ulster winger Trimble snatched a vital score just before half-time, making the line on the left flank with man-of-the-match O'Driscoll again supplying the final pass.
Clarke has four hundreds in his last 7 tests as captain, all of them vital scores.
