With just four wins from the opening 10 matches even a spot in the finals looked out of reach.

But on Saturday the Tigers proved momentum was a wonderful thing as their stellar second half of the season culminated in a Kelly Cup premiership.

Played at No. 3 Oval against RSL-Colts, Newtown Black battled to post 9-106 from their 40 overs before bowling Colts out for 89 to seal a low-scoring thriller.

"At Christmas we were no hope," Newtown Black captain Brett Wrigley said.

"This is what we had to do after our first half of the season and we weren't expecting it.

"But we got on a roll and had some momentum."

After winning the toss and batting, Wrigley (0) and Graham Baker (6) both departed early to give Colts the upper hand.

A patient 48-run partnership between top-scorer Tom Skinner (23) and Matt Ball (19) got Newtown Black back in the match.

The pair only managed to take the score to 2-24 after 20 overs but they stayed at the crease and continued to build.

But when Ball was dismissed by Adam Cuskelly it triggered a collapse of 3-6 and Newtown Black were suddenly 5-66.

A 30-run partnership between Andrew Walden (16) and Andrew Gardiner (16) helped the score past 100 as Newtown Black managed to bat out the overs.

Dane Cooper was the best of the Colts bowlers with 3-8.

"Once we got 100 I was pretty happy," Wrigley said.

"It was a bit of a psychological thing.

"Our strength has always been our bowling."

Gardiner then took three early wickets, including that of Colts captain Wayne Cole, and the men in red were in all sorts of trouble at 5-38 in reply.

But opener Lyndon Whitney, coming off 111 in the semi-final, stuck it out.

Newtown continued to strike and at 8-60 it seemed all over but Whitney found support in Ryan Davies.

The pair patiently worked the ball around and soon the scenario was a tense one with Colts needing 21 runs off five overs with two wickets in hand.

But Whitney soon fell for a hard-fought and respectable 45 and just four balls later Adam Wheeler bowled number 11 Adam Cuskelly and Newtown Black were premiers.

"It's good to win a grand final," Wrigley said.

"Last season we made the semis and made a mistake by not putting the covers on and Rugby beat us and then won it so this year was sweet."

The loss was a bitter one for Colts and captain Wayne Cole, who have now lost the past five Kelly Cup grand finals.