Brentwood earned the bragging rights over Wanstead in their Dukes Essex League Cup tie on Saturday.
The Premier Division rivals met in the second round at the Old County Ground, with Brentwood piling up 347-5 from their 50 overs.
Captain Aaron West (35) hit seven fours as he dominated a 46-run opening stand with Ed Ballard, who struck three sixes and 11 fours in a run-a-ball 85.
Ballard put on 135 for the second wicket with Essex youngster Will Buttleman, who fell two runs short of a century after hitting three sixes and 11 fours in an 86-ball knock.
And there were contributions from Jack Hebron (69 not out) and Ben Allison (31), as Zain Shahzad (2-58) and Nabeel Aziz (2-72) had most success for the Wanstead attack.
The Herons were reduced to 39-4 in reply, by Allison (2-19) and Harry Phillips, before Arfan Akram dug in to add 72 with Yuvraj Odedra.
Zoraiz Saeed (25) chipped in, as Odedra fell two runs short of a hundred after hitting five sixes and 14 fours in his 62-ball innings.
Aziz added 46 off 43 balls, with captain Joe Ellis-Grewal last man out for 63 as Brentwood sealed a 57-run win.
Upminster eased to an eight-wicket win over Shenfield, following a century from South African signing JJ Smuts.
Oliver Ekers hit an unbeaten 88 to steer the visitors to 236-7, with Usman Ul-Haq (40) and Max Bear (32) also making useful starts as Oliver Peck (3-36) took the bowling honours for Upminster.
Smuts dominated a 160-run opening stand with Pulkit Gupta (35) and hit four sixes and 21 fours in his 90-ball 130, before James Evans (45 not out) and Kiran Kullar completed the chase with eight overs to spare.
Hornchurch had a comfortable nine-wicket win over Old Southendian & Southchurch, who were dismissed for 178 at Harrow Lodge Park.
Billy Gordon (3-35) led the attack, with George Hankins (2-15), Adeel Malik (2-27) and Marc Whitlock (2-41) nabbing braces.
Ronnie Saunders hit 16 fours on his way to 79 off just 52 balls, putting on 154 for the first wicket with Paul Murray (64 not out) as Hornchurch reached their target in 21 overs.
Harold Wood celebrated a 72-run win over Oakfield Parkonians, after half-centuries from Taqi Abbas (73) and Shahbaz Khan (54) led them to 277.
Umar Choudhry (3-49) and Paran Kalley (2-54) had most success with the ball for Parks, who were dismissed in 41 overs.
Wickets were shared between Waqas Shafique (2-27), Ed Smith (2-31), Abbas (2-34), Khan (2-37) and Harry Thompson (1-59), while Umar Choudhry (50) and Osman Choudhry (40 not out) led the way with the bat for beaten Parks.
Billericay also booked a place in the last eight after an 18-run win at Hadleigh & Thundersley.
New South African signing Grant Roelofsen, 25, smacked 10 sixes and 15 fours in a stunning innings of 177 off just 131 balls to lead Billericay to 253.
And Ross Poulton (4-22) shone with the ball, as Matthew Bells (2-50) and Thomas Gibney (2-58) nabbed braces to help dismiss the hosts for 235 with an over remaining.
Ilford bowed out at Buckhurst Hill, after Sandun Dias hit nine sixes and 12 fours in his 134 off 78 balls to lead the home side to 350-8.
Captain Nigel Jacobs nabbed 2-44, with Prahathen Jayarooban (2-51) also bagging a brace for Ilford.
But after Aditya Nair (42) and Mohammad Ahktar (71) put on 99 for the first wicket, with Jacobs (29) and Dulen Abayakoon (22) also making starts, Ilford slipped from 152-1 to 224 all out.
Prithviraj Sarvaiya (4-38) did most of the damage with the ball for Buckhurst Hill.
Billericay entertain Chingford in the quarter-finals, while Harold Wood host Hornchurch and Upminster welcome Brentwood. Buckhurst Hill are at home against Chelmsford in the remaining tie.
The new Hamro Foundation Essex League Division Three season also began at the weekend, with Barking beating Rainham by 160 runs, Frenford earning a 55-run win over West Essex and Bentley beating Neo by five wickets.
Ardleigh Green & Havering-atte-Bower thrashed Redbridge by 173 runs, while Newham defeated South Woodford by four wickets, Hornchurch Athletic had a 93-run win at Woodford Green and Goresbrook lost by nine wickets at Walthamstow.
Other local clubs begin their league campaigns on Saturday, with play getting underway at 12.30pm.
Selected fixtures, Premier: Belhus v Wanstead, Brentwood v Chingford, Chelmsford v Shenfield, Colchester v Hutton, Hadleigh v Hornchurch.
Division 1: Billericay v Harold Wood, Ilford v Woodford Wells, Upminster v Gidea Park & Romford.
Division 2: Horndon v Old Brentwoods, Oakfield Parkonians v Leigh.
Division 3: Bentley v Ardleigh Green & Havering-atte-Bower, Frenford v Southend, Hornchurch Athletic v Barking, Newham v Stanford, Rainham v Springfield, Redbridge v Goresbrook, South Woodford v Woodford Green.
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