Wasps took another step towards the LV= Cup semi-finals with a hard-fought 21-14 victory over Gloucester at Adams Park on Sunday.
Trailing 14-3, Wasps' comeback was sparked by the arrival of scrum-half Joe Simpson off the bench in the 50th minute.
Simpson scored a try and inspired a Wasps side huffing and puffing in the face of a fading force.
Within minutes of a kick-off delayed by 15 minutes due to Gloucester's bus being held up in traffic, Simon Shaw and Gareth Delve were addressed by referee Martin Fox after a flare-up close to Gloucester's line.
Wasps kept pressing and were rewarded with a penalty after five minutes, conceded by Adam Eustace and kicked by Eoghan Hickey.
Shaw, forced out of England's squad in August because of a broken metatarsal, looked determined to remind the selectors he was back in business, charging at Gloucester's defence with ball in hand.
Freddie Burns missed a penalty for the visitors on 17 minutes but soon made amends.
After good work by flanker Apolosi Satala, Burns arrowed through a narrow gap for the game's first try and converted to make it 7-3.
Will Matthews kept Wasps from going further behind when he charged down a drop-goal attempt by Burns in the 34th minute and Gloucester were worth their interval lead.
Wasps changed things around for the second half, former England fly-half Dave Walder coming on for Hickey, who replaced Jack Wallace at full-back.
But within two minutes Gloucester had extended their lead.
Wasps made a nonsense of a simple kick ahead by Burns, whose second prod at the rolling ball went straight between the legs of Hickey.
Burns chased it over the line and went behind the posts to make his own conversion simple.
Wasps battled back and a fine example of ball-winning by Shaw armed Tom Varndell with the ball to attack Gloucester's left flank.
Olly Morgan showed Varndell the outside and the wing changed gear and raced over the line. Hickey's attempted conversion flew wide.
Walder missed a penalty on 53 minutes but Wasps regained the lead five minutes later following a Gloucester lineout blunder.
Ben Phillips overthrew close to his own line, Wasps pressure prevented Gloucester's defence covering and Simpson dived over from close range, Walder adding the conversion.
Hickey hit the post with a massive penalty attempt from halfway before things turned sour for Gloucester in the 68th minute.
Simpson scooped up a ball won against the head and, in their desperation to prevent a try, Gloucester killed the ball.
Walder rifled home the penalty and referee Fox sent Scott Lawson to the bin.
Another Walder goal after 75 minutes, rebounding inwards off the left-hand post, sealed victory.
For London Wasps:
Pens:Hickey, Walder 2
Tries: Burns 2
Cons: Burns 2
Yellow card: Lawson (Gloucester - 68th min)
London Wasps: 15 Jack Wallace, 14 Paul Sackey (C), 13 Ben Jacobs, 12 Lachlan Mitchell, 11 Tom Varndell, 10 Eoghan Hickey, 9 Warren Fury, 8 Hugo Ellis, 7 Will Matthews, 6 Dan Leo, 5 Richard Birkett, 4 Simon Shaw, 3 Joe Horn-Smith, 2 Joe Ward, 1 Charlie Beech.
Replacements: 16 Chris Whitehead, 17 Gabriel Bocca, 18 Ben Broster, 19 Marty Veale, 20 John Hart, 21 Joe Simpson, 22 Dave Walder, 23 Mark Odejobi.
Gloucester: 15 Olly Morgan, 14 Tom Voyce, 13 Henry Trinder, 12 Eliota Fuimaono-Sapolu, 11 Jonny May, 10 Freddie Burns, 9 Rory Lawson, 8 Gareth Delve (capt), 7 Jake Boer, 6 Peter Buxton, 5 Dave Attwood, 4 Adam Eustace, 3 Pierre Capdevielle, 2 Ben Phillips, 1 Nick Wood.
Replacements: 16 Scott Lawson, 17 Yann Thomas, 18 Greg Somerville, 19 Will James, 20 TBC, 21 Dave Lewis, 22 Carlos Spencer, 23 Tim Molenaar.
Venue: Adams Park