The Steelmen sit in third place in the Evo-Stik League South Division One Central following a third win in a row as they fought back from 2-0 down to win 5-2 at Welwyn Garden City on Tuesday night.
The victory saw them move to within four points of leaders Bromsgrove Sporting and to within two of second-placed Peterborough Sports.
Now Corby are preparing to take on Sports in a top-of-the-table showdown this weekend.
The Peterborough club got the better of the Steelmen with a 2-1 win in the reverse fixture back in November.
But boss Kinniburgh knows the latest clash between the two could well be one of the pivotal moments in what looks set to be a tight three-horse race for the sole automatic promotion place.
“It was a great fightback on Tuesday and it leads us into the biggest game of our season so far,” the Steelmen manager said.
“I think it is going to give his a massive tell on what is going to happen between now and the end of the season.
“You can call it whatever you want – a big game or a six-pointer. It’s absolutely huge for both teams.
“These are the sort of games that you want to be in. If you can’t get yourself up for this and enjoy it then you don’t really deserve to be in football at this level.
“This is one of those games where you need your players to step up to the mark and that’s exactly what I expect from our lads this weekend.”
Two goals from top scorer Elliot Sandy and one each from Bradley Fortnam-Tomlinson, Joel Carta and Steve Diggin, who returned to the club at the end of last week, completed the Steelmen’s midweek fightback.
And that came after they also won on the road at Kempston Rovers last weekend with Diggin, Carta and Sandy all on target again in a 3-1 success.