With a strong breeze at their backs in the first half, previous troubles with clearing passes through the backline not seen since round one came back to haunt them with the ball either bouncing to the receiver's feet or above their heads.
Pirates were also sloppy with their handling but made up for it with strong tackling.
Halfback Josh Navitio twice pounced on Border's slipups.
Nearing halftime, on three occasions the locals fumbled the ball just as they were turning it over at the breakdown from Pirates bursts.
Able to work forward from the ensuing scrums, Navitio cut through a half gap to dash over beside the posts.
Midway through the second half, he would parry a loose Border pass for the intercept and sprint nearly 50m for what proved the matchwinner with desperate winger Aaron Vadiga chasing in vain.
While lock Sam Madams finally drove over for Border to have a chance right at the death, Fraser Middleton could have scored earlier after Vadiga caught a Mark Davis chip kick but the normally reliable fullback spilled an inside pass you would expect him to catch 99 times out of 100.
Disappointed coach Peter Richardson knew they cost themselves dearly the tactics were right, the execution was not.
"It came down to a few missed opportunities, we panicked a bit.
"We just didn't cash in and you've got to when you're playing semifinal rugby.
"The things that didn't happen were the bounce of the ball, the luck of the game the guys never gave in."
His opposite Phillip Morris was delighted his team stepped up under pressure rushing Border who made "unusual errors".
"I was rapt the way they played into the wind, first half attacked into the wind."
He heaped praise on first-five Denning Tyrell, who was at his probing best when taking on the defensive line, while Navitio and captain Lasa Ulukuta complemented that effort.
Young referee Ben Lourie had an excellent match with the whistle being firm but fair.
Pirates had the perfect start after Border spilled possession in their own half Navitio and Tyrell combining with fullback Josh Marwick for winger Clive Stowers to crash over despite two tacklers.
Border replied in the 13th minute when a Vadiga chip just evaded him but Border earned a penalty at the ruck, with halfback Lindsay Horrocks taking a quick tap and burrowing over.
Pirates then pressured Horrocks remorselessly at the back of scrum, with Navitio claiming a try before being ruled offside.
Davis' normally accurate passes lost direction, although Pirates couldn't capitalise.
Finally utilising the wind, Davis put Pirates back with his kicks and got his team in position to bang over a penalty after 25 minutes, 10-5.
Pirates front row of Turner, Junior Tume, and Aisea Vaivela kept going straight up the guts their team prospering from the scrappy play as Border just could not regather clean ball.
Navitio's great try had the visitor's blood up at 12-10 by halftime.
Border's pack were penalised in front for Marwick to extend the lead on the hour, then six minutes later Navitio was gone for the winner.
Horrocks, Vadiga and Madams all tried to carry their team home, as Border camped in Pirates half but could not find a way through.
Turn to Page 30 to read about Ruapehu's semifinal win over Taihape.
Integrity Motors Pirates 22 (Josh Navitio 2, Clive Stowers tries, Josh Marwick pen, con, Denning Tyrell con) bt Waverley Harvesting Border 15 (Lindsay Horrocks, Sam Madams tries, Mark Davis pen, con). HT: 12-10.
