The Blacks produced a resolute defensive effort to shut down Merewether 25-17 in the minor semi-final at No.2 Sportsground on Sunday.

Next is a rematch with Wanderers, who prevailed 35-10 in their last meeting in the qualifying final a fortnight ago.

"We have momentum, which is valuable," Thomas said. "But we can't be hot and cold. Against Wanderers last time, we were cold. This week we were OK. Our set piece needs a lot of work and our composure. Sometimes we overplay our hand and we don't need to. Just keep it simple."

Maitland played direct against the Greens and were rewarded.

Pat Robards came in at inside centre, shifting Carl Manu out a spot and Chris Logan to fullback. Lachlan Bradford, who has played either fly-half or fullback all season, slotted in on the right wing.

"We had to change it." Thomas said. "Pat Robards straightened us up. An ex-leaguey always does that for you. It stopped us from going sideways and created space out wide."

Bradford opened the scoring in the fourth minute when he came from the right to support left winger Dale Clacherty after Manu had made a bust on the edge.

Merewether replied almost instantly. Halfback Eli McCulloch sold a dummy at the base of the ruck, raced 20 metres and linked with Lachlan Milton who crashed over beside the posts for a 7-5 lead.

Ten minutes later, Robards fought off two defenders and popped a one-arm pass around the corner to Bradford for his second.

Bradford added a penalty to extend the gap to 15-7.

The Greens hit back just before half-time through Dylan Smouha for 15-12 at the break.

The Blacks opened the second half with a penalty to Bradford. Then with Smouha in the sinbin for a late tackle, McCormack produced a show and go from a scrum 20 metres out to open a 25-12 advantage.

Kosta Sykiotis crossed down the short side in the 54 minute to give the Greens a sniff.

They had the ascendancy in the scrum and had their chances. They bombed two tries with passes that went behind the target and into touch.

"That didn't cost us the game," co-coach Mick Gill said. "It was our attitude. We didn't want it. There was no intent. From early int he first half I could see we were off. It just wasn't a Greens performance."