After 10 matches of 14, the Steelbacks are second in the North Group table, a point behind leaders Lancashire Lightning, and three clear of fifth-placed Yorkshire Vikings.
The top four of both the North and South groups qualify for the last eight, with the top two in each section guaranteed home advantage in the quarter-finals.
Northants, who are unbeaten in their past five fixtures, play three matches against top four rivals in the next four days, a run of games that will go a long way to sealing their qualifying fate.
They travel to fourth-placed Derbyshire Falcons on Tuesday (start 7pm), host third-placed Birmingham Bears on Wednesday (6.30pm) and then entertain Yorkshire on Friday (6.30pm).
Their final game is then at Leicestershire Foxes on Friday, July 1, but Sadler will be hoping his players may well have guaranteed a top two place by then.
"I think if we win two games then that would potentially seal a home quarter-final, without doing the maths," said the Steelbacks head coach ahead of the date with a Derbyshire side that have won five matches in a row.
"It is now quite congested up there, and there are five teams that could end up in any order, while Notts (who are seventh) have games in hand so they could still make a bit of a late charge.
"Derby are the form team now, Birmingham were the form team at the start, Lancs and Yorkshire are always there or thereabouts and then there is ourselves who are playing good cricket.
"But we just have to focus on what we do, take it one game at a time and hopefully get a bit of good luck on the way.
"Then we should be through, and that would be a great effort from the lads."