The rate rose to more than eight an over as the match drew to a close, but High School timed their run to perfection. As Parsons and Sharrock upped the tempo, so Collegiate's fielding started to disintegrate.
Parsons hit his fourth ton of the season - 116 not out in 82 balls, with six 4s and one over the ropes - while Sharrock's unbeaten 47 was a confident and controlled effort played under pressure.
Up the road at Victoria Park, runs were less plentiful. If not quite a spinner's paradise, then turn was certainly favourite in the Tech v United dogfight.
Tech were in a state of collapse early on before Josh Plumridge and Tariq Alam came together for the sixth wicket in a mighty salvage operation. A resilient Plumridge hung on for an unbeaten 73, while Alam mixed defence and attack for his 65, but the 179-6 total always looked on the low side.
United newcomer Sakun Jindal picked up a couple of wickets with his spinners, though the former Punjab state junior rep is more noted for his batting.
Back in India, the 22-year-old earned a scholarship from John Wright, the former Indian coach and now Black Caps chief, which took him to the Southern Institute of Technology in Invercargill. He was chosen for Southland's Hawke Cup team but had to return to India for family reasons without playing a game. Now he is in Wanganui and will do some coaching for Cricket Wanganui and target next season's Hawke Cup squad.
Unfortunately for United, he failed to deliver with the bat, but Andrew McCaa's half-century (four 4s and one 6) had them comfortably on course for the win.
However, the match turned with Tech employing Hayden Englefield's off-spin at one end and Nathan Clarke's leggies at the other. Englefield had McCaa caught and bowled and suddenly wickets were tumbling.
United slipped to 121-7 - read that as 121-8 as they again only had 10 men with Englefield taking four wickets and Clarke deserving better than his one victim.
But with the spinners' 10-over spells used up, Tech could not press home their advantage and Jamie Whiteman put on an invaluable 48 with Neil Kirkwood and then saw United home with last man Andrew Cording at the crease.
Marton Saracens were also down to 10 men, though whether it would have made any difference against Marist is open to question.
Several batsmen got a start, but none progressed beyond 19 as Saracens stumbled through their innings.
Needing 119 for victory, Marist didn't hang about, scoring at eight runs an over to secure an early finish.
Opener Chris Stewart picked up where he left off with last week's unbeaten 119, scoring a rapid-fire 60 not out to leave Marist level with United at the top of the table with four wins each.