Gordon's, who play a second- round cup game against Madras College at Countesswells this weekend, had been expected to be sharp following their successful three-match tour in Canada during the October break but Watson's were much more aggressive at the breakdown and much fitter in the later stages.
Watson's, whose tally included two tries from Dominic Johnston, the son of former Scotland centre David Johnston, scored 25 of their points in the last 13 minutes of the game.
Gordon's also suffered in the Brewin Dolphin Under-16 Cup match at Myreside, losing 77-3 to a slick Watson's, who play Banchory Academy tomorrow.
North Berwick High School showed their readiness for Saturday's Cup game with Watson's by holding Dollar Academy to one try apiece, the Clackmannanshire school running out 13-7 winners thanks to the kicking of full back Adam Dearden.
In Glasgow, Heriot's continued their good form with a 17-5 win over Hutchesons' Grammar School at Auldhouse, with two tries from winger Mike Firoozi, one from scrum-half Euan Hooper and a conversion goal by Grant Mollison.
In Perthshire, Strathallan await Merchiston Castle this weekend in what will be a hard game for the hosts. Merchiston showed why they are among the favourites for cup honours this season with an impressive win over Edinburgh Academy at Colinton on Saturday.
Strathallan then have a hectic cup schedule, playing their three round two matches in the space of seven days with games against Edinburgh Academy, Loretto and Bell-Baxter High School.
Meanwhile, in the Borders Under-18 league, Gala Wanderers showed a return to form with a 40-29 win over Hawick PSA while Kelso Quins edged out Peebles Colts with an 18-12 victory. Quins, who are positioning themselves for a place in the quarter-finals of National Youth League Cup, face Selkirk Youth Club, another side competing for a cup place.
In England, Loretto won the inaugural Rugby Schools Nations Tournament B Section, held in conjunction with Gloucester RFC, which brought together six invited sides from Ireland to join 16 selected school teams from Scotland, England and Wales.
Loretto won their pool with wins over Fettes, Wesley College, Brandon Grammar School and Pembrokeshire College and in the final beat Filton College on a penalty shoot-out after a 6-6 draw.