Pietserse twice denied his former Amakhosi colleagues from the spot on Saturday, first thwarting Bernard Parker’s extra-time penalty before making another save from George Maluleka during the lottery of spot kicks after 120 minutes at Soccer City finished 1-1.
And speaking to KickOff.com, Pieterse says: “Firstly I’m just happy for the team to have progressed to the next round.
“I must admit it felt great saving Parker’s penalty. It was important as it still kept us in the game.
“The other one from George was a bit nerve-racking as penalty kicks are like a lottery and you never really know which way it’s going.
“But as a keeper, I did what I had to do in order for my team to win,” adds the 25-year-old.
Matsatsantsa are well on their way to making history in the lucrative Ke Yona competition by becoming the first side to successfully defend the title they won last season when they beat Mamelodi Sundowns in the final.
SuperSport, Orlando Pirates, Golden Arrows and Chippa United are the four teams in Monday night's semi-final draw, but Pieterse has downplayed suggestions they are among the favourites to win the competition again.
United also have top-three ambitions in the Absa Premiership and next travel to title-chasers Bidvest Wits on Tuesday with three vital league points on the line.
“There’s still a long way to go but we are just taking it one game at a time. We play Wits next in the league and they are purely our focus now,” Pieterse continues.
“We’ve lost some momentum against Sundowns and Baroka so we need to get back to winning ways to get our league campaign on track.”