The only goal of the game was scored on 22 minutes by 21-year-old left winger Lee Martin, and despite an improved second half performance from the Buccaneers, who rested the likes of Teko Modise, Benson Mhlongo and Moeneeb Josephs, the visitors held on for the win.
United centreback John Evans had the first chance of the game, but he headed high over the bar from Chris Eagles’ corner on nine minutes.
Senzo Meyiwa in the home goal then had to make a smart save low to his right from Martin, who was causing Happy Jele all sorts of problems down the lefthand side.
It was not long before the duo tangled again and once more Martin came out on top. Wes Brown flicked a header on for Frazier Campbell, who rose highest to head into the path of Martin, and he showed good strength to hold off Jele and poke the ball past an onrushing Meyiwa for the opening goal.
It could have been 2-0 soon afterwards, but Meyiwa was alert to rush out of his area and win the ball with his feet when Campbell looked through on goal.
After Tevez had seen a shot deflected narrowly wide on 34 minutes, United felt they should have had a penalty when Martin was upended in the penalty area. Their case looked strong, but the referee signaled a corner instead, and Rio Ferdinand received a yellow card for his protests.
The halftime whistle brought some relief to Pirates, who were losing the shot count 14-1 at the break.
Tlou Segolela had the first chance of the second period as he ran onto Lebohang Mothibantwa’s excellent 40-yard ball, but despite getting behind the defender, the youngster fired wildly over.
Pirates were beginning to bring their wide players into the game more, and Segolela on the right, and Bennett Chenene on the opposite flank, looked the most effective form of attack for the Buccaneers.
Mothibantwa then unleashed a drive from 35-yards that Ben Foster in the United goal palmed over the bar for a corner.
Substitutes Wayne Rooney and Paul Scholes combined as the former set up the latter on the edge of the area, but Scholes’ powerful drive was straight at Meyiwa and the keeper beat it away for the corner.
At the other end, excellent work from Jele set up substitute Joseph Makhanya, whose vicious shot was excellently saved by Foster.
Pirates now face Kaizer Chiefs in Port Elizabeth on Thursday, with the winner of that match earning the right to face the Red Devils in the Final of the Vodacom Challenge at Loftus Stadium in Tshwane on Saturday.