The Seasiders stole the points in this highly-charged derby match away to the Quins on Saturday, with number 10 Tom Lewis scoring a late try to seal the win.
It was the home team, however, who had most of the possession in the first half and notched up 10 points through a penalty from outside-half Dean Lawrence and a try from winger Lee Scourfield, which Lawrence converted.
Former Quins outside-half Lewis kicked a penalty in the first half to keep Tenby in touch and then added two more to claw his side back to within a point, before he grabbed a try late on when he intercepted the ball 40 metres out and raced through to put the Seasiders in front, converting his own try for good measure.
Lawrence still had time to kick a penalty for the Quins, but it was all too little too late as Tenby notched up their sixth victory out of seven games.
Tenby United team: Aled Griffiths, Dan Colley, Mark Heywood, Gavin Brace, Paul Luger, Tom Lewis, Rhys Thomas, Lee Tucker (capt), Mike Lewis, Simon Griffiths, Wyndham Williams, Ifan Davies, Sam Smith, Harry Bolton, Rob James. Replacements: Nicky Guymer, Gareth Edwards, Adam Ball, Johnny Lane, Ben Cray.