Second-half strikes from Tsweu Mokoro and Stanton Lewis were enough to see Roger Palmgren’s side picking up all points on offer.
The match got away to a slow start with both sides losing possession cheaply in the opening minutes.
The first chance of the match fell for the home side in the 11th minute when Lewis sent in a brilliant cross that found Ramson Zhuwawo unmarked in the box but he didn’t make a proper connection and sent his header wide from close range.
Clifford Mulenga almost scored at the other end in the 18th minute when he received a cross from Phenyo Mongala. The Zambian controlled the ball and unleashed a left-footed shot but Tapuwa Kapini was well-positioned to make a low save.
A minute later, Cecil Oerson initiated a quick-break with a pass to Mongala and the winger delivered a low cross into the box but it was too strong for Mulenga who was arriving at the far post.
Celtic should have opened the scoring in the 31st minute when Kapini spilt the ball from a corner but the experienced goalkeeper recovered well to tip the ball over the bar to deny Letladi Madubanya’s header, keeping the score unchanged in the first half.
Usuthu started the second half brightly with Stanton Lewis forcing a save from Patrick Tignyemb five minutes after the break, but soon the match turned scrappy as both sides lacked creativity in the middle of the park.
The opener eventually arrived in the 74th minute as a result of poor defending when Thabo Ntethe tried to shield the ball over the line but he was dispossessed by Zhuwawo who then played it across for Mokoro to finish.
The goal brought the match back to life and Celtic almost equalised straight after the restart but Mongala’s shot crashed against the upright with Kapini well-beaten.
The victory was sealed in the 86th minute with Zhuwawo playing the perfect pass for Lewis who showed his class with a calm finish inside the box.
Usuthu have now picked up seven points in their last three league matches and they have moved up to 13th place on the log.