Both teams lost their opening sectional game but stormed back to effectively win five straight knockout matches and clinch the biggest prize in NSW rep bowls.

The Open side lost two rinks to one and by 17 shots in the section opener against Sydney Central and South but turned the tables against the undefeated Zone 13 outfit in the final, with a brilliant 70-53 win.

The NSW Inter-Zone Sides Championships featured Seniors (Over 60s) and Open titles played over six days at Sydney-based Grandviews and Olds Park bowling clubs.

After enjoying fine, dry weather for the Seniors event, the Open's championship was struck down by cold, wet, miserable conditions at the quarter-final stage leaving some matches decided via a concession, including South West NSW (Zone 8) conceding defeat to Zone 16 after trailing 60-38 on 49 ends.

Earlier the Zone 16 Seniors lost their opening match to Zone 13, 66-62, and faced elimination when trailing Newcastle in round two, but fought back to win by a shot 68-67.

From there the Illawarra Seniors were unstoppable, clinching second spot in their section with a 75-49 rout of Far North Coast (Zone 1) and then edging past North Coast (Zone 14) 56-54 in a tense quarter-final.

Zone 16 then beat Sydney Northern 58-47 in the semi-finals and neighbours South Eastern NSW (Zone 7) 63-47 in the final.

It was Illawarra's third victory in the most prestigious state event for Over 60's bowlers and first trophy since the back-to-back championships in 2009 and 2010.

All three Illawarra rinks won their match in the final and played crucial roles in the title success.

Skip Rick Malley and partners Charles Johnston, Geoff McGillivray and Brad Rossiter rebounded from a heavy loss in round one to claim a pivotal 25-21 rink win against Newcastle; plus had wins in the quarter-finals, semi-finals and decider.

New Australian Jackaroos Seniors representative Robbie Warren and his partners Brian Suckley, Ted Clarke and Brett Pritchard won three of their first four games including clinching a quarter-final spot for Zone 16, plus then won 21-17 against North Coast in the quarters.

Brian Harriott and partners John Ritchie, Jack Forbes and Neil McCall were the backbone of Illawarra's triumph winning five of their six games.

The Zone 16 squad featured bowlers from six clubs, with Terry Boniface the reserve and Terry Seton the team manager.

''We had 13 fantastic players,'' Seton said.

''There were no standouts, everyone contributed. The spirit was amazing and they can all hold their heads high with a win like this.''

It was also a great effort by South Coast-based Zone 7 who like Zone 16 finished runners-up in their section, and then went on to make their first NSW Inter-Zone final at Seniors or Open level.

Zone 7 upstaged Section 1 winner Zone 13, 57-51 in the quarter-finals and then beat Sydney South West 60-56 to march into the final.