The village side turned the form book upside down in the limited over competition on Sunday, beating visiting Division One leaders New Milton by 37 runs.
The Division Two home side, having been put into bat, scored 164-7 off their 20 overs.
South Africian Ari Karvelas led the way with an unbeaten 65 and was well supported by Matt Kerr (31) and Louis Lynch (20).
Nick Park (43) and Ryan Beck (33) looked to have built the foundation for a New Milton win as they guided the side to 80-2, but their departures started the rot and the visitors slumped from 113-4 to 127 all out.
A jubilant Hartley captain Teale said: “Any score at Hartley can be chased, but we bowled tight throughout. Jack Cockram took four wickets, Tommy Flanders was brilliant in a pressure situation and Louis Lynch kept the pressure on.
“I think in the end we were shocked they ended up 37 runs below our total, as they are unbeaten in the division above us.”
The previous day, Hartley lost by eight wickets in their latest Division Two game at Portsmouth.
Karvelas recorded his best score of the season so far, as he hit an unbeaten 67, which saw him hit a six and eight fours.
Unfortunately, only Chris Jolley (32) gave him any support as Hartley were bowled out for 160.
Portsmouth then cruised to victory thanks to an unbroken third-wicket partnership of 116 between Robert Jones (70) and Jack Marston (45).
Hartley have just a league game this weekend, when they entertain Havant II, and both sides have won just once in the 50 over format this season.
Captain Teale is unavailable for the game, so Matt Digweed will skipper the side, which will be otherwise unchanged, with Jack Hersh returning and taking the place of the skipper at the top of the order.
Karvelas’ excellent weekend will see the South Africian move up the batting order to four or five.
The Hartley skipper Teale said: “It was a great T20 win and now we want to build on this in the league and get a run going.
“We know we are as good as any team in this division, but it is matter of putting our minds to it and playing as a team and not as individuals.”