Steels stunned D&P Trophies Sunderland Club Carpet Bowls League champions and holders Grindon to edge through to the 321 Knockout Cup semi-finals.
In a fiercely fought first rink, Steels got the perfect start by winning 27-21. It was too close to call in the second rink, but Steels squeezed home 25-23, giving them an eight-shot lead going into the final rink.
Grindon set about their challenge in the right manner but just fell short by three in the end, winning 25-20 in a humdinger of a battle.
Steels now meet Plain Farm, who booked their semi-final place with a 71-70 win over Hetton.
A tense opening rink ended 23-22 to Plains Farm, and they just got over the line in the second, taking it 25-23, putting them three ahead overall.
Hetton played their hearts out and fought all the way in the decider, taking the victory 25-23 to miss out by a single shot.
Town End Farm progressed at the expense of Grangetown in a thrilling encounter. The home side were three players down and had to concede nine shots overall.
In the first rink, Grangetown were in control, leading 21-9 after five ends, but Town End hit back to reduce the deficit to 27-21 by the end.
Town End had to scrap hard for a 24-24 draw in the second rink, but they sealed victory with a 36-18 victory in the final rink, sealing an 81-69 overall triumph, despite a spirited effort by Grangetown.
Results: Steels 72 Grindon 69, Grangetown 69 Town End Farm 81, Hetton 70 Plains Farm 71
Semi-final draw: Steels v Plains Farm, St Leonard’s v Town End Farm