Amakhosi needed to return to winning ways following their 2-1 loss to Mamelodi Sundowns, and Ernst Middendorp needed to change things around and make sure that his bounces back.
They went into the encounter on the back of a single defeat in their last four matches in all competitions.
Ekstein, who won the man of the match award on the night, started in midfield and found the back of the net just after Castro had scored the for the visitors in the closing stages.
Middendorp kept faith in Virgil Vries despite his costly mistake which helped Sundowns move to within touching distance of leaders Wits.
The Nambia international looked very confident this time around even though his club fans gave him a hard time for taking too long to restart play from goal-kicks.
It was perhaps a sign of desperation on the side of the Amakhosi fans who dominated the small venue in Braamfontein.
This game was also important to Chiefs' rivals, Orlando Pirates, who needed Wits to lose in order to remain two points behind them on the PSL log whilst at the same time move up the ladder as they currently find themself fifth on the standings.
Middendorp's side isn't counted among genuine title contenders, but their win over Wits has certainly blown the title race wide open although there's still a long way to go before the finish line.
Chiefs kept the same 3-5-2 formation as the German mentor wanted to rectify mistakes of the past game in this regard.
The first half didn't really produce fireworks as both sides cancelled each out going into the dressing rooms.
After a slow start to the second half, Chiefs took the lead through Castro, who connected with Siphosakhe Ntiya-Ntiya's cross into the box, beating Darren Keet through the middle to make it 1-0.
Amakhosi fans out in the stands regained their voices and began to rally behind the team more with the players doing the most on the pitch.
The match opened up with Wits now looking for a goal of their own as they committed numbers forward in the process.
Gavin Hunt's men relied on the likes of Elias Pelembe for pace, but they forgot to keep things tight at the back, especially after the introduction of Bernard Parker, who found Ekstein unmarked inside the box to put the game to bed.
There was drama in the closing stages of the game as Robyn Johannes was sent off by referee Victor Gomes deep into stoppage time to see Wits finish with 10 men.
Wits' management surrounded Gomes after the final whistle, but there was nothing they could do as Chiefs players left the pitch quietly pocketing all three points ahead of their Sunday's Caf Confederation Cup match against Zesco United.