Runaway-leaders Craneswater A held their nerve to pinch a 7-5 victory over arch-rivals Copnor A.
Late doubles by Gary More and Steve Cole gave the reigning champions the vital edge.
Mike Talmondt had given them the lead.
But Steve Toms and Scott Compton hit back to keep it close.
Craneswater Z kept their hopes alive with an 8-4 home success over Copnor D.
Ian Carter and Nigel Ward decided it, with Ward registering a 42 in the process.
Al’s Club and Craneswater Q played a couple of days early and the Portchester men were very pleased with an 8-4 triumph.
Charlie Bishop, Mark Kingswell and Matt Hannam were all on target to thwart Graham Tregardine.
Leigh Park managed a 7-5 win against Emsworth thanks to Mark Raynor and Pete Ferguson.
Tommy O’Neil kept it close as Bill Parsons suffered a rare loss.
Cowplain A chalked up a similar win against their Z team.
Heath Smith gave the former Ville outfit a strong start.
Then Dave Rees and Jamie Wilson turned it around with a brace apiece.
Division two favourites Bellair A saw off North End Bowls 9-3.
Ade Pledge replied for the city boys after Greg Jones, Steve Whitney, Phil Skinner and Andy Smith had won the first eight racks of the evening.
Craneswater R are in second spot but have a bye to come.
They hammered Alexandra 9-3 despite an early double from bowler Matt Sheath.
However, Martyn Power, Harry Yard (32), Andy White and Andy Carter were unstoppable for the Southsea gang who face an anxious wait in the final session.
Copnor E recorded a 9-3 win against basement side Broadoak and it could have been more.
Claire Branscombe and Steve Scott pinched two frames on the black.
Pete Rook is in great form and he was backed up by Norman Bradfield and Phil Ledington.
Pompey Royals took their tally to 11 wins, beating Copnor F 9-3.
Steve Orchard compiled a 37 to join Paul Tinsley and Jon Challacombe on the winners rostrum.
Dave Chiver’s outfit are now sure of the silverware in the bottom tier.
Rob Dandy is still keen as mustard and his Craneswater squad drew with Leigh Park B.
Brian Elsegood rubbed out an away double by young Colin Ricketts.
The Workies are third but could finish nearer the bottom when other sides catch up on the fixture list.
Cowplain C just got the better of their B team with a very hard-fought 7-5 scoreline.
Gary Curtis struck first before C team skipper Ray Axton and Kelvin Connor had the final say.