NTOB lost the New Zealand Club Championship Bay qualifying match to CHB on Christmas Eve.
CHB lost to New Plymouth Marist United in the Central Districts' play-offs in Palmerston North by two wickets to lose the right to represent the region against other major association winners in Auckland.
In the Bay one-day competition, NTOB amassed 262 to be all out in the 49th over at Cornwall Park, Hastings.
Bronson Meehan scored 100 runs while fellow opener Christian Purchass added 44. No 3 Indika Senarathne contributed 46, smashing Cornwall bowler John Jowsey for three consecutive sixes before holing out to mid-wicket somewhat softly.
"Bronson was solid but Indika, who dropped from opening, has found some form," Diack said of Meehan who faced 147 balls in 186 minutes to yield seven boundaries and two sixes.
"Indy was just about to do something special but he got himself out so he'll be a little disappointed," Diack said.
Cornwall seamer Ben Jackett took 4-40 from 10 overs.
In reply, the hosts' wheels came off in 40 overs for 160 runs. No 4 Seb Langridge, exuding confidence since returning from the New Zealand A Provincial Tournament in Christchurch, top scored with 45 runs. No 6 Jono Hall was unbeaten on 44 while opener Jayden Waters added 31.
"We dropped one [NZ club champs] but we don't want to drop any other competitions," Diack said of his 2012-13 English style one-day (60-over) champions although Cornwall have won the HBCA T20 tournament last October.
NTOB are also on track to comfortably claim the overall premier club men's title this summer when all the points from all three formats of competitions are tallied.
In the other game at Nelson Park No 3, Havelock North were too strong for NOBM, coming away with an eight-wicket victory.
Skittling Marist for a paltry 140 in 45.1 overs, the Todd Astill-captained villagers eclipsed the total with 141-2 in 31.3 overs.
Jack Ward top scored for Marist with 40 and tail-ender Tom Forsdike added 25.
In a concerted frugal effort, medium pacer Jared Priest took 27-3 from 10 overs, including two maidens.
Miserly Sam Prescott, Matt Taylor and Kurt Richards took two wickets each and Jeremy Ketel was wicket-less from 10 overs but conceded 24 runs to claim five maidens.
CD squad member Ben Wheeler took 1-23 from nine overs, including two maidens.
"Ben's bowling at 80 per cent but he's bowling a good length and line," Astill said of the Stags seamer who is coming back from an injury lay-off.
In Havelock North's innings, No 3 Graeme Tryon was 64 not out and Astill was unbeaten on 53.
Forsdike matched the villagers' frugality with a wicket-less spell from eight overs, including two maidens, bleeding only 16 runs.
"We didn't have to take too many risks chasing a small total," Astill said, delighted with the win after losing two close encounters to NTOB and CHB.
"We were in the hunt in those two games but we bowled full and misfielded, but today we had a solid allround performance."
Astill said with the Hawke Cup campaign over, the one-day play-offs should be a humdinger.
With CHB away in Palmy North, Taradale CC had a bye so their game will be played this Sunday.
