Zakhele Lepasa came in for the injured Gabadinho Mhango, Thabang Monare was handed his first start while Happy Jele dropped to the bench. Meanwhile, Chiefs had only one enforced change, as Ramahlwe Mphahlele replaced the injured Reeve Frosler in the line-up.
Khama Billiat had a great chance to get the opener for Amakhosi in the tenth minute after a mistake at the back saw him charge clear inside the box, but his strike brushed the top side of the crossbar.
Leonardo Castro should have made it 1-0 for Gavin Hunt's charges ten minutes later after Billiat delivered a cut-back in the centre of the box but the Colombian scuffed his shot wide, with only Richard Ofori to beat,
However, it was the who got the opening goal as Lepasa repaid Josef Zinbauer's faith by nodding home Terrence Dzvukamanja's cross for his first goal of the season.
Pirates should have added a second goal on the stroke of half-time after Vincent Pule beat the ofside trap to go clear on goal on the left flank but he put too much pace on his pass, which evaded Lepasa and Dzvukamanja.
Chiefs had more urgency in the second stanza after Happy Mashiane and Bernard Parker both came on for Lebogang Manyama and Nkosingiphile Ncobo just before the hour-mark, as Siyabonga Ngezana came close to equalising with a header that was saved by goalkeeper Richard Ofori from close range.
However, Pule doubled the lead for Zinnbauer's troops in the 66th minute after he mistimed a cross from Innocent Maela inside the box but wrong-footed Njabulo Blom and Ngezana to have space for a low shot past shot-stopper Daniel Akpeyi.
The Glamour Boys were committing numbers going forward in the closing stages and they were caught on a counter-attack in the last eight minutes as Lorch capitalised on a mistake at the back to go clear on goal, kept his composure and fired a strike past Akepyi to make it 3-0 for Pirates.
The Buccaneers were defending deep in the dying minutes, denying Chiefs any chances of getting an away goal and held on to clinch a 3-0 win ahead of the second-leg clash next weekend.
Pirates: Ofori, Hlatshwayo, Nyauza, Jooste, Maela, Motshwari, Monare, Pule, Lorch, Dzvukamanja, Lepasa
Subs: Sandilands, Mntambo, Mako, Zungu, Makaringe, Makgaka, Hotto, Ndlovu, Jele.
Chiefs: Akpeyi, Mphahlele, Cardoso, Ngezana, Zulu, Baccus, Blom, Ngcobo, Manyama , Billiat, Castro.
Subs: Khune, Parker, Katsande, Mathoho, Sasman, Mashiane, Ntshangase, Sifama, Lesako.