A 30-run win at Mulsanne Park, combined with defeat for leaders Scothern reduced the gap to 10 points.
Caistor batted first and useful contributions from Danny Bevis (24), Rory Ronaldson (19) and Olly Barrick (32), all batting around Jim Parker’s 50, helped the visitors post 176 all out, as they were dismissed on the penultimate ball.
For Nettleham, there were four wickets each for Wakeel Shah and Lewis Bromfield.
In reply, Nettleham again had some useful scores, but lost wickets steadily.
Caistor used five bowlers, but five wickets from Rory Ronaldson and two apiece from Sean Wooley and Pete Briggs saw the hosts bowled out for 146 after 38 overs.
The Premier league is very close with seven matches remaining, and even more so after Saturday’s results when third-placed Cherry Willingham beat leaders Scothern, and now less than 20 points separates the top four.
On Saturday, Caistor Firsts face an important match at home to fourth-placed Haxey (1pm start).
* Market Rasen CC First XI were without a fixture on Saturday and dropped to eighth place in the Premier Division.
They return at home to Grimsby Town on Saturday at rase Park (1pm start).
Their Second XI also did not have to face a ball as they were handed the 20 points after opponents Holton-le-Clay Seconds were unable to fulfil the fixture.