They were just two points ahead of fifth-placed Te Puia Springs, who beat bottom-of-the-table Gisborne Park 8-4.
Had Colbert lost, it would have meant a sudden-death playoff between PB and the Springs for that fourth spot.
Instead, PB (2) will face third qualifiers Patutahi in a sudden-death semifinal at Gisborne Park this Saturday, the winners advancing to another do-or-die clash with the losers of the 1 v 2 semifinal.
Those slots were filled by PB (1) on 30 points and Tolaga Bay on 24.
The winners of their tie will advance directly to the final.
Unbeaten PB (1) sneaked home 7-5 over fellow joint defending champions Patutahi on Sunday.
They improved their perfect morning foursomes record over the series so far to six from six but suffered their first afternoon singles matchplay losses – Pete Anderson going down to Hukanui Brown and Peter Kerekere losing 1-up to Shayde Skudder in Skudder’s first appearance of the series.
Patutahi went into the tie without the services of electrician Tony Akroyd, who suffered a serious finger injury at work and is out of action for several weeks.
Fortunately for them, they were able to call on Skudder as it was a Sunday round. Skudder has been unavailable for the previous rounds — both held on Saturdays — as he plays premier club rugby for YMP.
With YMP having the bye tomorrow, Skudder will again be available for their crunch semifinal.
Despite another team defeat, Park had their best result of the series so far. It included singles wins to Sel Peneha and Tom Teneti.
These were their only wins of the three rounds.
Tomorrow, Round 3 of the Endeavour men’s interclub handicap pennants will also be held. Te Puia Springs is hosting the round. Waikohu lead the series on 38 points, from Tahunga on 30 and Tolaga Bay on 28.