Gloucester reached the European Challenge Cup final after a thrilling derby struggle with Worcester at Kingsholm.

Worcester were eight points ahead at one stage as their fly-half Shane Drahm went through the scoring book.

But that and a tremendous effort from the Warriors was not enough to deny Gloucester their second victory in successive weeks over their M5 motorway neighbours.

World Cup winner Phil Vickery, who shocked everyone at Kingsholm by announcing he was quitting Gloucester after 11 years, sat in the stand to watch his now former club's assault while recovering from a third back operation.

The match was crucial for the Warriors as the only way they could qualify for the next Heineken Cup was to actually win the Challenge Cup competition as they are too far down the Guinness Premiership to realistically envisage qualification via that route.

A piece of indiscipline when scrum-half Peter Richards, in the mix to challenge Leicester's Harry Ellis for the England number nine shirt now that Matt Dawson has retired, was raked 39 metres out from the Worcester posts gave fly-half Ryan Lamb the first points when he banged over a penalty.

However, that lead did not last long as opposite number Drahm replied just moments later.

It was all pretty even before a dazzling piece of brilliance from the home team saw them get the opening try.

Warriors full-back Nicolas Le Roux put up a high kick from his own half down field.

This was caught by Richards who counter-attacked. The scrum-half played the rugby equivalent of a footballing one-two with Lamb to outfox the defence.

Eventually, the number nine fed winger James Simpson-Daniel who glided past two tacklers on the right wing to go over from 22 metres.

And, in almost a mirror image of last week's match, Gloucester went 15-3 up when Simpson-Daniel and captain Peter Buxton drove to the Warriors 22 before a quick ruck saw Lamb put centre Anthony Allen away through a massive hole in the opposition midfield.

The England Under-19 international sprinted the 20 metres unopposed to the posts for his fly-half to add the extra points from the conversion.

That second try woke the Warriors up. Drahm scorched through a gap between Lamb and Allen on halfway to pass to Le Roux in support.

The full-back, with men around him, was tackled 20 metres out.

A few minutes later from another attack, ex-Gloucester prop Tony Windo dropped an easy pass with the line begging.

The pressure told as scrum-half Matt Powell fed Drahm from a set-piece five yards from Gloucester's line and he again found the gap between the centre and stand-off.

Drahm was tackled on the line by England centre Mike Tindall but had done enough to stretch and put the ball into the scoring zone, adding the conversion himself to put his team back into the match.

Worcester should have been at least level five minutes before the break when wing Uche Oduoza was put away inside his own 22 before passing to his captain Pat Sanderson.

The England international charged 40 metres and had support in space to his right but he cut into the middle and found the only defender left in the home 22 as the ball popped out forward.

But the Warriors captain made up for his mistake in emphatic fashion when, after a burst from 30 metres by number eight Kai Horstmann, who linked with lock Phil Murphy, Sanderson was given the scoring pass from five yards and Drahm's conversion put the visitors in front for the first time at 17-15.

Then the dazzling Drahm booted a 39-yard drop-goal before adding his second penalty to put his team eight points to the good before Lamb reduced the arrears with his second successful penalty.

Worcester upped the pace of the game but replacement full-back Ludovic Mercier dragged Gloucester back to within two points with a penalty near the halfway line.

In a mirror image of the previous weekend, Gloucester snatched the lead as Lamb boomed a high kick onto the 22 where Tindall and Mercier recovered it from Le Roux.

Gloucester won the ruck for Lamb to put a cross kick to the left wing.

Mark Foster caught the ball superbly and dived in at the corner. Lamb's marvellous touchline conversion left Worcester almost down and out.

Another penalty from Lamb put Gloucester two scores in front going into injury time and that was enough for the win and a place against either London Irish or Newcastle who play their semi-final tomorrow.