Northants County kept up the pressure on Northampton as they moved within three points of the runaway leaders with a 16-8 home victory against Rushden.
Although the visitors secured a big win in game five, County were always in control of the match as they recorded comfortable victories in all the other ties.
County, who travel to Northampton in their last match, still need to get something this weekend at Cold Ashby, who remain bottom of the table after losing 10-1 away to Overstone Park.
Defending champions Collingtree Park are through to the semi-finals after recording their ninth victory in a row, and seventh this season, with an 8-2 success at Silverstone.
Despite trailing early on, Collingtree kept their form as Roo Smith and Adrian Kilshaw (two holes), Tom Low and Stephen Low (one hole), Alistair Biggin and David Messom (four holes) and Mike Clarke and Ron Major (one hole) sealed the win.
Brampton Heath missed an opportunity to guarantee a semi-final place with back-to-back away defeats to Staverton Park and Wellingborough.
After winning their first six games this year, Brampton lost 8-2 at Staverton before they were beaten 12-3 by Wellingborough, who can still overtake the leaders if they are successful in their last three fixtures.
Hellidon Lakes were at their clinical best at home to Priors Hall as they sealed a last four spot with a 28-0 thrashing of the Corby club.
Needing a win to top the standings, the result was never in doubt once Hellidon’s Gary Osborne and Richard Barnes (eight holes) and Richard French and Roy Trim (nine holes) romped to victory in games two and three respectively.
Kingsthorpe had to settle for second place after they completed their campaign with a couple of mixed results as they followed up a 12-3 defeat at Priors Hall with a 17-5 home success over Kettering.
Farthingstone produced arguably their best performance of the year at the last time of asking as they fought back from an early deficit at home to Hellidon to record a 16-7 victory a week earlier.