Pirates’ goals were scored by Gilbert Mushangazhike, Rudzani Ramudzuli, Teko Modise and Tlou Segolela, before Sanele Majola pulled one back for Usuthu.
Pirates started the half strongly, with chance after chance. Modise ballooned a shot over the crossbar in the tenth minute, after a nice build and excellent work from Ramudzuli.
In the 15th minute Pirates had another good opportunity to take the lead, when they were awarded a free-kick on the edge of the area, but again Modise skied his shot over the bar.
In the 24th minute Lebohang Mokoena ran at the Usuthu defence, but his shot went straight to the keeper.
Less than a minute later Mushangazhike put Pirates ahead with a shot from close range to make it a well-deserved 1-0.
The Zimbabwean had another chance in the 33rd minute, but Kalililo Kakonje managed to parry the ball over for a corner.
A minute later, however, Ramudzuli doubled Pirates’ lead with a good shot from inside the box.
In the 38 minute Usuthu had a chance to pull one back, when they were awarded a free-kick just outside the box, but Bafo Biyela’s shot went over the crossbar and the match went to half-time 2-0.
In the 50th minute AmaZulu had another opportunity to bring one back, when Dumisani Ngwenya located Thabo Mabaso with a great pass, but Pirates’ keeper Senzo Meyiwa pulled off a great save to keep Bucs safe.
In the 57th minute Modise put the game beyond doubt with a coolly-taken penalty, after Belux Bukasa Kasonga was adjudged to have handled the ball in the box.
Tlou Segolela closed the scoring for Bucs in the 74th minute, with a spectacular goal – a powerful strike from left of the penalty area.
Usuthu got a consolation goal in the 85th minute, when they were awarded a penalty after Mokoena fouled Mabaso in the box. Majola converted, and the game ended 4-1.
The result puts Pirates at eighth place with 42 points, just ahead of Golden Arrows on 41. If Arrows had managed to beat Ajax in their final game, they would have beaten Pirates to the top eight spot, but the KwaZulu Natal side could only manage a 2-2 draw.