They failed to convert early pressure into points and then gave away some soft scores. However the home side fought hard for the win and move up to fourth in the league.
They’ll have to tighten up for their final next month though, based on this evidence.
Aberdeen took the opening score after 15 minutes but Grangemouth hit back immediately through skipper Thomas Skelton, though his conversion hit the post.
On the half hour mark Wanderers collected their second score. Once again they countered from deep and good support play ended with a try in the corner. This time the conversion was off target. A few minutes later a break by the Aberdeen scrum half almost produced another score but he was bundled into touch 5 metres from the line.
However the visitors won the lineout and moved the ball wide to beat the cover and score. This time the conversion was successful.
Just on half time the Stags were back on the attack and scored through Stangoe for a 19-10 half-time deficit.
On 47 minutes Forsyth dived on the ball for the score but Skelton was again off target with the conversion. A few minutes later the Stags took the lead as they collected the bonus point score. The forwards had a series of drives close to the line before the ball was moved wide for Shannon to run in for the score. This time Skelton was on target.
Having taken the lead Grangemouth seemed to switch off and this allowed the visitors back into the game. Wanderers continued to press and they took a tap penalty close to the line. The Stags defence stalled the attack but the eventual unconverted score and two-point lead made for a nervy ending.
With just six minutes to play the Stags were awarded a penalty 35 metres out. Skelton’s kick sailed between the uprights for a narrow advantage to the home side. He added the final kick, and points on the whistle too.
Next up is the shield final at Glensburgh against Strathmore on February 16 KO 2.30pm.