Just 24 hours after a 125-run humiliation at the hands of Birmingham Bears in the first game of the competition at Edgbaston, Steelbacks showed what they are all about as they claimed a 31-run victory at a packed Wantage Road.
Australian import Chris Lynn, on his home debut, smashed 83 from 46 balls and Ben Curran 71 from 43 as Northants posted a huge 223 for four.
And then, despite Durham getting their innings off to a flyer and racing to 114 for one before the halfway stage, the Steelbacks battled back to bowl the visitors out for 191 to claim their first win in in any competition this season.
That Durham collapse was sparked by a superb spell of bowling from 20-year-old left-arm wrist spinner Freddie Heldreich, who claimed three for 22 in his four overs - including the crucial wicket of opener Graham Clark who hit 54 from just 30 balls.
And it was a result and performance that delighted Sadler, who knows all too well that the showing in the defeat to the Bears wasn't good enough.
"It's a fickle game isn't it? The important thing is to not get too down if you lose, and to not get too up if you win," said the Steelbacks coach.
"But that was a really good performance in terms of bouncing back and showing some character, I thought that was really good from the lads and I am proud of them tonight.
"The openers played beautifully, and I am really pleased for Ben because he played the game really well.
"We know it is in there with Benny, and obviously Chris Lynn is world-class, but in that partnership they both complemented each other really well.
"The way they went and attacked different ends, and being a left and a right hander obviously helps.
"They set it up really nice for us, and when you get a really big opening partnership like that and you have some firepower to come you can keep going."That was why we were able to post a massive score, and I thought we then packed it up with the bowling.
"I thought we bowled well, I thought we were unpredictable which is good, I thought we went to our options well and we mixed it up.
"Then obviously a special mention to Freddie who bowled magnificiently, and he was probably the difference in the end."
Looking back on Durham's collapse from a good position, Sadler felt the scoreboard pressure of having scored 223 played a big part.
"Wickets are crucial, but with a big score on the board they have got to keep going, they have no choice but to do that," said the head coach, who claimed his first win in charge.
"You just feel that at some point they are going to cloth one, and that's where you pick up a couple of catches.
"With the run-rate so high, we knew they were always going to be under pressure no matter what.
"I thought we stayed calm, and Cobby (Josh Cobb) is quite good because he stays calm out there, and I thought he captained the team really well.
"So I am really please with the performance, but rewind 24 hours it was a different feeling, so let's not get too up and not get too down if we have a tough day.
"It was really important we put a performance in tonight.
"We got a bit of stick on Thursday night, and it is uderstandable when we don't play as well as we can.
"So I am really pleased for the home crowd that we have put on a show, with bat, ball and in the field.
"We have a weekend off now where the lads can enjoy it a bit more, you always do after a win, but we will reflect for a little bit and then it all starts again Monday (at Notts Outlaws) at nought for nought."
Friday was also the first time in Sadler's time at the club, due to the Covid pandemic, that there has been a full crowd in for a match, and he relished the occasion.
"It was absolutely fantastic," said the Yorkshireman, who joined the club as assistant coach in January, 2020.
"It just kept getting busier ad busier, and it kept getting louder as the day went on.
"I thought the fans were superb and they are massive for us, they are the 12th man.
"Every time Lynny hit a six they kept getting louder, so I am really pleased, it was a good night for everybody."