Auckland were reduced to 75 for 5 after medium-pacer Ed Nuttall ran through their top order with a career-best 3 for 17. What followed was an unbroken partnership of 81 between de Grandhomme and SM Solia (29 off 21), that came off just 42 balls, and took Auckland past their target of 151 with ten balls to spare. 21-year-old left-arm spinner Jeremy Benton was taken for 30 runs in his solitary over during the course of Auckland's chase.
Earlier, Cam Fletcher's 37 and a 16-ball 35 by Andrew Ellis were the only significant contributions for Canterbury as they folded for 150 after electing to bat. Canterbury lost regular wickets, with legspinner Tarun Nethula returning career-best figures of 4 for 18, while pacers Donovan Grobbelaar and Tymal Mills took three wickets each in an innings where only five batsmen got into double figures.
The win - their fourth in as many games - kept Auckland at the top of the table.
Tom Bruce continued his fine domestic form with an aggressive 74 off 41 to lead Central Districts to a nine-run win against Wellington in Nelson. Central Districts scored a competitive 181 for 5 before Wellington fell short despite a quick half-century by captain and opener Hamish Marshall.
Wellington's chase saw a strong opening stand of 55 in the Powerplay, between Marshall and Michael Papps before they lost three wickets in the next four overs. Marshall went on to score his 15th T20 fifty, off 35 balls, but the rising asking rate led to his wicket, for 52 off 37, after Luke Ronchi and Grant Elliott fell for low scores. Wellington needed 69 in the last six overs and brought it down to 29 off 12 but Michael Pollard was bowled for 22 and they fell short despite an unbeaten 26 off 17 from Luke Woodcock. Left-arm spinner George Worker finished with a frugal 2 for 25 from four overs.
Put in to bat, Central Districts lost Mahela Jayawardene for 5 in the second over before Worker, the other opener, and captain Will Young fell within the space of four balls at the score of 46. However, Bruce and Dane Cleaver revived them with a stand of 61, as Bruce did the bulk of scoring to take them past 100. Cleaver scored 15 and Bruce's belligerent knock, with eight fours and three sixes, powered them till the last over that helped them go past 180. Elliott took two wickets but almost all bowlers leaked too many runs.
Neil Broom celebrated his call-up to the ODI squad against Bangladesh with an unbeaten 54 off 41 balls as Otago registered a thumping eight-wicket win against a Northern Districts side that featured as many as six international players at the Bay Oval in Mount Maunganui.
Northern Districts put on 157 after electing to bat, through contributions from Tim Seifert (41) and Corey Anderson (39). The pair brought impetus to the innings that was otherwise kept in check by tight bowling from Anaru Kitchen, Neil Wagner, and Warren Barnes, who took 5 for 46 in the ten overs among them.
Otago's innings wasn't of the same brand, with openers Kitchen and Hamish Rutherford (39) racing off to a 51-run stand that took just 4.3 overs. Their separation brought a brief halt in momentum, but an unbroken stand of 91 for the third wicket between Broom and Michael Bracewell (41 off 27) took Otago to victory with 15 balls to spare.