Kevin Morgan makes a rare break for Swansea

Henson, 19, was the shining line, booting all his kicks at goal and providing glimpses of a rare talent.

But a Swansea side containing nine Welsh internationals should have been far more clinical in attack.

They created few chances, and several players looked as if they were going through the motions.

Edinburgh scored the solitary try, Scottish international full-back Chris Paterson touching down in injury time, and although fly-half Gordon Ross slotted three penalties, they failed to take advantage of Swansea's off-day.

The Welsh club go to Bath next Saturday, and will not have been encouraged by news of the West Country side's stunning 14-6 victory over Biarritz in France.

Ross kicked two penalties while Henson landed a penalty and dropped a goal during a forgettable opening 30 minutes when Italian referee Giovanni Morandin repeatedly whistled for the slightest infringement.

A combination of his fickle officiating and the game's abysmal standard understandably frustrated the home supporters.

Swansea finished the first half on top though, with Henson finding the target on two further occasions and then slotted another penalty just after the break.

Edinburgh's Steve Scott spreads the play

Swansea though, still could not produce anything constructive with ball in hand.

And it was not until six minutes from time when Henson hauled them into a 21-9 lead that they looked comfortable.

But even then, they had to endure a nervous final few minutes.

Paterson pounced for a try two minutes into stoppage time that substitute Duncan Hodge converted, and Edinburgh knew that a quick-fire repeat would have given them victory.

But Swansea held on, and Plumtree now faces a tough week on the training field lifting his players for the Bath challenge. On this evidence, Swansea looked nothing like quarter final material.

Swansea: Pens: Henson 6. Drop Goals: Henson.

Edinburgh: Tries: Paterson. Cons: Hodge. Pens: Ross 3.

Att: 2,750

Swansea: Kevin Morgan; Richard Rees, Shaun Payne, Scott Gibbs (capt), Brian Lima; Gavin Henson, Robbie Jones; Johnny Marsters, Garin Jenkins, Ben Evans, Tyrone Maullin, Andy Moore, Geraint Lewis, Colin Charvis, Hywel Jenkins.
Reps: Robert Jones, Nik Witkowski, Arwel Thomas, Chris Wells, Andrew Le Chavalier, Lee Jones, Dean Thomas.

Edinburgh: Chris Paterson; Derrick Lee, Marcus Di Rollo, Kevin Utterson, Conan Sharman; Gordon Ross, Graeme Burns (capt); Allan Jacobsen, Steve Scott, Craig Smith, Matt Jolly, Alastair Davidson, Andrew Dall, Graham Dall, Simon Taylor.
Reps: Joel Brannigan, Carlo Di Ciacca, Matt Taylor, Tony Walker, Iain Fairley, Duncan Hodge, Calvin Howarth.

Referee: G Morandin (Italy)