The game started with terrible overhead conditions and it was Mambos who started with a bang and from a Donaldson cross Alan Brown headed home.
Anderson came close with a shot from outside the box and then Taylor was in on goal but Park came out to block.
Methlick drew level on the 30-minute mark when a good move was finished by Sleigh.
Anderson beat two players and crossed for Taylor but he headed just past the post. At the other end Timmins came close with a drive from the right side of the box.
Sleigh came to the rescue for Methlick when he cleared off the line from a Gourley shot.
Just one minute into the second half, Mambos went in front from a free kick which Gourley scored at the back post.
Mambos were awarded a penalty which Brown took but he was foiled by Burnett who made another good save.
Alan Donaldson added a third for Mambos before Gourley netted a fourth.
A mistake by Bonner let Brown in to rifle a left foot shot into the corner of the net from 15 yards. James Timmins got his Mambos sixth and Donaldson finished the scoring netting number seven.
In the first half Methlick held their own against their opposition but Mambos came out much stronger from the start of the second period and dominated the second 45 minutes running out comfortable winners.
Thanks have been expressed to Kris Hunter of Soccerworld, Aberdeen for his continued support of the League Cup in the Buchan Welfare Football League.
METHLICK: Burnett, G. Finnie, Sleigh, Brown, Bonner, Ligertwood, Low, Smith, Taylor, Stewart, Anderson. Subs: Barrack, Watt, Bruce, Minty.
MAMBOS: Park, Donald, Booth, Brown, Mark Duncan, Gourley Timmins, Fraser, Brown, L. Stephen, Donaldson. Subs: J. Stephen, A. Norris, Alan Norris, Martyn Duncan, McBain
Meanwhile, in the Buchan Welfare League Longside Thistle faced Peterhead Pensioners and the home side dominated the first half but were finding it hard to get a goal until on 3o minutes a corner was swung in and only cleared to the edge of the box where William Filson curled it right into the top corner of the net.
It stayed that way until the second half where the Pensioners were pushing hard for an equaliser and it came on the hour mark from a corner Hendry headed in at the near post.
It looked as though it was going to end in a draw until David Fraser sent in a dangerous cross which Neil Buchan latched onto to fire home the winner.
Grange United faced second place Mambos and the away side did lead by two goals scored by Alan Brown until the last 15 minutes when Grange came storming back to score four goals.
AJ Buchan scored with a spectacular lobb from the edge of the box, Marc Walker from the penalty spot, Ryan Webster and then Michael Waddell after brilliant footwork by Marc Walker.
Methlick continued with their good form of late when they put five goals past Harbour Lights without reply.
Their goals came from Kevin Taylor with a double and one each from Kris Dear, Martin Smith and Stuart Anderson Jnr.
In another league game Ardallie had Cuminestown as opponents and this was expected to be a close affair.
The match ended in a 2-2 draw. Scoring for the home side were Scott Bartlet and Jamie McNeil and replying for the visitors were John Jamieson and Shaun Mitchell.
Buchanhaven Rangers played hosts to Cuminestown in terrible overhead conditions and the match ended with a 2-0 win for the visitors.
The goals came from Stephen Howitt and Daryn Bruce.
Ardallie faced Harbour Lights and the home side gathered another three points in a 5-1 win.
The winning goals came from Stuart Park netting a brace and one each from Scott Bartlet, David Clark and Jack Wright and replying for the away side was Robbie McKean.
Monday, June 18:
League - Longside Thistle 2, Phd Pensioners 1; Grange Utd 4, Mambos 2; Methlick 5, Harbour Lights 0; Ardallie 2, Cuminestown 2.
Thursday, June 21:
League - BH Rangers 0, Cuminestown 2; Ardallie 5, Harbour Lights 1.
Soccerworld League Cup final - Mambos 7, Methlick 1.
Fixtures for Thursday, June 28:Cuminestown Shield quarter-finals - Grange United v Phd Pensioners; Mambos v Longside Thistle; Cuminestown v Methlick; Ardallie v BH Rangers (kick-off 7pm).
Monday, July 2:
League - Ardallie v Harbour Lights; Mambos v Phd Pensioners; Cuminestown v Grange United; Methlick v BH Rangers (kick-off 7pm).