Porterfield's previous Twenty20 best was 65 against Glamorgan at Bristol
Will Porterfield smashed 83 as Warwickshire opened their FL t20 campaign with a five-wicket win over Durham at Chester-le-Street.
Ian Blackwell hit an unbeaten 46 as Durham made 151-3 from their 20 overs.
But, once Ireland captain Porterfield arrived at the crease to register his highest score in the competition, the result was in little doubt.
Porterfield hit 10 fours and two sixes before getting himself run out with one run needed as his team reached 155-5.
On a glorious evening at the Riverside, the left-hander repeated his demolition of the Durham attack in a CB40 league match at Edgbaston 12 days ago.
Winning with 11 balls to spare was a solid way for Warwickshire to start after last summer's frustrations when they topped the North Group, only to lose to eventual winners Hampshire in the quarter-finals at Edgbaston.
On the bowling front, Steffan Piolet played a big part for the Bears, putting on the brakes by taking 2-19 from his four overs after Phil Mustard (38) and Gordon Muchall (35) had got the home side off to a lively start.
Gareth Breese was Durham's best performer with the ball, taking 2-24.
Durham captain Dale Benkenstein told BBC Newcastle:
"After a good start we looked like we'd get about 170, maybe a few more, but we couldn't get any boundaries late on and we fell short of where we'd have liked to be.
"The fact we batted the 20 overs was a positive, but I think we struggled to adjust going into this one on the back of so many four-day games.
"However we have time to prepare now for the next match and, with 16 games in the competition, you can recover quite easily if you don't start too well."
BBC Sport's Bears reporter Clive Eakin:
"A very encouraging start for Warwickshire. The way they reined Durham in after the game had appeared to be running away from them in the early stages was impressive.
"Stefan Piolet may not like being regarded as a Twenty20 specialist but his bamboozling variations seem perfectly suited for the shorter game. And Will Porterfield's innings was perfectly measured showing how much the experience of playing international cricket appears to have helped him.
"With Ant Botha and Chris Woakes still to come into the side it's looking a well balanced Twenty20 squad."
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