Aberdeen Grammar head coach Ali O’Connor paid tribute to his forwards who dominated in the mud and rain at Musselburgh, scoring five of the six tries in the 38-32 win.
The victory keeps the Rubislaw side in third place in the Premiership, six points behind leaders Marr.
O’Connor said: “Not for the first time, there were some big performances form the forwards. Robin Cessford was immense.
“We relied on our pack to get us on to the front foot and in the conditions today that was really important.
“We put the pressure on Musselburgh, forcing them into making mistakes, earning us a try bonus point, and enabling us to go into next week’s game against GHA with optimism.”
The Stoneyhill side opened the scoring with a try in nine minutes when winger Sandy Watt nipped over, giving scrum-half Danny Owenson the easiest of kicks.
Grammar prop Ross Anderson drove over for a try from short range, converted by centre Tom Aplin, to level at 7-7.
Home winger Gregor Tait outpaced the Aberdeen defence before his opposite number did the same at the other end, giving him his seventh try of the campaign.
Both were converted, but it was Musselburgh who oved ahead with an Owenson penalty which only served to spark a burst of scoring from the visitors.
First over was Cessford with two fine dashes to the line, a second from Anderson and a final effort from flanker Chris Jollands, two of which were converted by Aplin.
In the midst of the Grammar scoring spree, the hosts kept in the game with touchdowns from Tait and lock McKinstry, and a penalty from Owenson.
Grammar club captain Doug Russell underlined the contribution made by Cessford and No 8 Greig Ryan, saying: “These two were standouts on a day made for forwards.”
© Jack Nixon
Musselburgh: James Ferguson; Sandy Watt, Rory Smith, Rory Watt, Gregor Tait; Paul Cunningham, Danny Owenson; Robert Stoss, Paddy Portsmouth, Colin Arthur; Willliam Fleming, Graeme McKinstry; Cameron Pryde,Max Outram.
Replacements: Euan Bonthron, Jack Haynes, Calum Champion, Aidan Reddick, Tom Foley.
Aberdeen Grammar: Tommy Morrison; Nathan Brown, Murray Mitchell, Tom Aplin, Doug Russell; Sam Knudson, Jamie Troup; Calum Reddish, Ben Inglis, Ross Anderson; Nat Coe, Robin Cessford; Chris Jollands, Will Alton, Greig Ryan.
Replacements: Jonny Spence, Andrew Cook, Dominic Wallen, Mungo Somerville, Craig Shepherd.