Old Boys made it 15 wins from 15 as it beat Kurow 35-12 on Saturday.
The team will play Athletic Marist in Saturday's semifinal after Valley beat Athletic Marist 33-21. Excelsior will meet Valley in the other semifinal after beating Maheno 35-7 at the Maheno Domain.
Excelsior scored five converted tries, proving too strong in the backs, although the Maheno forwards led by Jamie Townsend playing at No 8 gave as good as they got. However, Excelsior's ability to spread the ball wide was the difference between the two sides.
Three minutes into the game, power running from Excelsior second five-eighth Kaituu Kaufana saw him break tackles and race 50m to score.
Seven minutes later, Billy Guyton chipped ahead on halfway. Fullback Tim Milmine was on hand to force the ball loose and hooker Dan Sinnamon dived over in the corner.
Four minutes into the second half, a try to first five-eighth Jason Forrest was converted by Guyton to take Excelsior out to 21-0.
Maheno first five-eighth Tom Dwyer intercepted a loose Excelsior pass to race 55m to score. Michael Hore converted.
A try to lock Jason Mills and a Guyton conversion took Excelsior out to a 28-7 lead.
Shortly after, referee Paul Mulligan ruled that Kaufana's tackle on Hore was dangerous and flashed the red card, meaning that Excelsior may be without him for the semifinals.
A further Guyton break saw him inpass to winger Matt Pearson who raced across for Guyton to convert.
Old Boys led Kurow 14-9 at halftime after Kurow had done most of the attacking. However, turnovers at vital times saw Old Boys run in tries to hooker Sam Kula and second five-eighth Hamish McCulloch, with Fala Fagasoaia converting both tries.
Kurow put points on the board when Fijian fullback Kameli Rakoko scored an unconverted try.
Old Boys struck back with tries to winger Omega Masoe, Adam Barnard and lock Sale Pi'I before Kurow's Gus Jansen touched down.
A fiery fightback by Athletic Marist in the third quarter was not enough to down Valley.
Mark Roney kicked an early penalty to give Valley a 3-0 lead. In the 25th minute, Valley second five-eighth Hamish McKenzie scored and then Valley fullback Rowan McKenzie scored.
He added two further tries before halftime, then Sione Pangata scored for Athletic Marist which Matt Egan converted, giving Valley a 27-7 halftime lead.
Seven minutes into the second half, lock Jon George surged over after some fine forward play from Athletic Marist, with Egan adding the conversion to make it 27-14.
A try to Nova Saone in the 54th minute brought Athletic Marist to within six points of Valley but Marist held on to win 33-17.
- Terry O'Neill
