Celtic came out top after a Vuyani Ntanga stunner in the 75th minute proved to be the decider as they notched up their second win of the Absa Premiership season.
Pirates did have the first chance, however, after Ayanda Gcaba had his first minute shot at the back-post cleared narrowly off the line.
Celtic fought back to end the half the stronger of the two, testing Mpontshane on a number of occassions.
The introductions of Lerato Lamola and Musa Nyatama in the second half paid off for Larsen as home side surged forward and find the net through a header from Ntanga, after a pin-point ball from Phalane on the left flank.
Pirates pushed for the equaliser late-on, and Kermit Erasmus came close in stoppage time but his headed effort was straight at Mpandle at his near-post.
Despite taking a risk with eight changes to the starting line-up, the Maritzburg-born tactician will be well pleased with his troops heading into the MTN 8 semi-final second leg on the weekend.