Wasps kept alive their hopes of a fourth successive league title by winning an epic Guinness Premiership clash at Kingsholm as they roared into the play-offs.

England flanker Joe Worsley scored two tries, including a 75th-minute clincher, to book a semi-final appointment with Sale Sharks tomorrow week.

But it was rough justice on Gloucester, whose play-off hopes disappeared despite blistering performances from teenagers Ryan Lamb and Anthony Allen.

The 19-year-olds stung Wasps, scoring 27 of their team's points, while substitute wing James Bailey took Gloucester 10 points clear through a 59th-minute try, but Worsley's double, a Paul Sackey try and 22 points from unflappable full-back Mark Van Gisbergen saw the visitors prevail.

Fly-half Lamb contributed 17 points and Allen claimed a try double, yet Wasps had just enough in the tank, showing amazing character to fight back from 32-20 adrift to leave Gloucester fifth and out of the play-offs.

Wasps, searching for a first win since their Powergen Cup final triumph against Llanelli Scarlets on April 9, welcomed back England stars Worsley and Josh Lewsey following substitute appearances during the 56-37 loss to London Irish last time out.

Lewsey partnered Stuart Abbott in midfield, but wing Ayoola Erinle suffered an injury during the warm-up and Sackey answered a late call, while Joe Ward took over from injured French hooker Raphael Ibanez and skipper Lawrence Dallaglio made his 150th Premiership appearance.

Gloucester boss Dean Ryan kept faith with young talent such as Allen, Lamb and full-back Olly Morgan, yet the west country club's stars of tomorrow faced a huge character test, trying to end Wasps' title hopes.

Ryan had vowed his team would not be shackled by nerves, and so it proved as Gloucester roared into a ninth-minute lead.

Wasps' much-vaunted blitz defence - breached nine times by Irish last Sunday - was opened up when Allen stormed through a huge gap and then scorched outside England wing Tom Voyce in exhilarating fashion.

Lamb failed to land the conversion, yet Allen's touchdown stirred Wasps and Van Gisbergen edged them ahead by slotting two penalties and frustrating the home side's attacking instincts.

Wasps sensed another opportunity to rattle Gloucester as they capitalised on some poor tactical kicking, setting up an imposing platform that saw Worsley prosper when he collected Lewsey's close-range pass.

Van Gisbergen's conversion opened up a 13-5 lead, and there was no stopping the champions as Gloucester showed glimpses of their inexperience by lacking structure under pressure.

Wasps, in contrast, kept possession alive superbly, and they made it 20 unanswered points during a devastating 16-minute spell when Van Gisbergen cut an unstoppable angle inside Gloucester's 22 and pocketed a try that he also converted.

Gloucester were left floundering, and although Lamb kicked a penalty just before the break, Wasps had a foot in the play-offs by establishing an emphatic interval advantage.

The home side knew they had to strike first after the break, and it took them less than two minutes following half-time switches that saw centre Mike Tindall and scrum-half Peter Richards replaced.

Number eight James Forrester caught Wasps napping from the base of a scrum, and before the visitors could regroup, Allen gathered Lamb's superbly-placed kick for his second try.

Lamb's conversion cut the deficit to five points, before Wasps were town apart by a blistering 80-metre move sparked by Lamb's long pass that found wing James Simpson-Daniel clear in space.

Simpson-Daniel required no second invitation to stretch the Wasps defence in both directions, and when substitute scrum-half Haydn Thomas acted as link-man, Lamb sidestepped his way over for a breathtaking score.

It was a majestic effort by the teenager, who then hoisted Gloucester five points clear through a conversion and penalty after Worsley was sin-binned for obstructing home lock Alex Brown.

Remarkably, Gloucester had scored 17 points in six minutes, and they finished an astonishing third quarter by conjuring another inspirational try when Lamb's long pass sent Simpson-Daniel on a weaving 60-metre run that ended with Bailey touching down.

Lamb converted from the touchline with a 12,500 capacity crowd in raptures, but Van Gisbergen's third successful penalty at least gave Wasps hope, trailing 32-23.

Wasps' champion pedigree had been seriously questioned, but just when they looked down and out, Sackey's pace undid Gloucester, scoring a try that Van Gisbergen converted to leave the champions just two points adrift.

Worsley then completed the fightback, confirming Wasps' semi-final place and ending an unforgettable contest that had star quality stamped all over it.