Sekhukhune United became the second Premier Soccer League club to advance to the MTN8 semi-finals after beating TS Galaxy 3-2 at the New Peter Mokaba Stadium on Saturday.
The Rockets now join Pirates, who also advanced after their 2-0 victory against Polokwane City.
Meanwhile, the visitors took an early lead when Mpho Mvelase scored in the 13th minute. The experienced midfielder found the back of the net with a close-range strike to put his side in the driver's seat.
The Rockets doubled their lead in the 40th minute; Victor Letsoalo took advantage of poor defending by Babina Noko to fire past Renaldo Leaner.
However, Sekhukhune United reduced the deficit almost immediately when Grobler headed past Tape Ira to score in the 42nd minute.
The former SuperSport United star scored again in the 64th minute to peg back the Rockets. Grobler's second goal rejuvenated Babina Noko, who went ahead to score their third and winning goal in the 69th minute through Vusimuzi Mncube.