Gloucester fought back from 10-0 down to claim victory for the second time this month over Saracens at Kingsholm in a tremendous Aviva Premiership clash.
The Cherry and Whites beat a lacklustre Sarries a fortnight ago in the LV= Cup, but the Londoners put on a much-improved display this time only to come away with a losing bonus point.
The win moved Gloucester above Saracens into fourth place in the table.
However, it was Saracens that started the stronger as they dominated territory in the opening quarter and gained their reward.
Fly-half Owen Farrell, whose fluffed his first effort the cup game, guided it this time between the posts from 30 metres to get the visitors up and running.
Saracens then enjoyed a concerted spell of pressure inside the home 22 but were denied a chance of scoring by some stout defence, particularly by excellent loose-head prop Nick Wood and full-back Olly Morgan.
But, when ex-England lock Alex Brown was sent to the sin-bin after 20 minutes for a late tackle on Farrell in midfield, the Londoners took their chance to move further ahead.
They pressurised the Cherry and Whites inside the home 22 and, when the ball went out to the left-hand touchline, winger James Short showed a great turn of pace to score his second Premiership try in successive weeks after making his league debut against Bath six days earlier.
Farrell's conversion put Saracens 10-0 ahead and well worth their lead.
That shook Gloucester into action and they finally got on the board when fly-half Nicky Robinson, the former Wales number 10, landed a 25-metre penalty.
Saracens were one pass away from scoring a second try as a superb move saw wing Dave Strettle feed scrum-half Richard Wigglesworth who in turn put lock Hugh Vyvyan clear.
However, Vyvyan's return pass to the number nine went astray with the line at ex-England cap Wigglesworth's mercy.
The tables turned towards the interval after Farrell's second penalty restored the 10-point gap.
Gloucester embarked on a prolonged attacking spell in the Saracens' half, with a Robinson penalty hitting an upright before Vyvyan was sent to the sin-bin for not clearing away from a ruck.
The Cherry and Whites went for glory twice with attempted driving line-outs from penalties in the visitors' danger zone but were pushed back both times and only came away from Vyvyan's absence with another Robinson shot at goal.
Robinson reduced the arrears to four points for the home side with his third penalty of the match as the match picked up speed.
Both sides battered each other between the 22 metre lines, with some outstanding handling movements the highlight.
But Gloucester took the lead for the first time with 16 minutes of the game remaining, the score leading to punches being thrown by both sides.
Wing Charlie Sharples raced down the right wing but, as he was running towards the posts to make Robinson's conversion easier, he and Saracens centre Kameli Ratuvou went flying into the advertising boards behind the dead-ball line.
The two teams reacted with their fists as referee Sean Davey tried to restore order.
When things calmed down - Davey took no action - Ratuvou was stretchered off and Sharples left the pitch dazed.
Robinson increased Gloucester's lead to six points with a fourth penalty but Saracens mounted a sustained attack to win the game in a pulsating finale.
Home wing James Simpson-Daniel produced a try-saving tackle on Strettle, prop Nick Wood saw the yellow card for dragging a ruck down metres from his line and replacement scrum-half Nick de Kock ran into the referee with time up as Gloucester held on.
Pens: Robinson (4)
Pens: Farrell (2)
Yellow cards: Brown, Wood (Gloucester), Vyvyan (Saracens)
Gloucester: 15 Olly Morgan, 14 Charlie Sharples, 13 Tim Molenaar, 12 Eliota Fuimaono-Sapolu, 11 James Simpson-Daniel, 10 Nicky Robinson, 9 Dave Lewis, 8 Luke Narraway (capt) 7 Andy Hazell, 6 Brett Deacon, 5 Alex Brown, 4 Dave Attwood, 3 Paul Doran-Jones, 2 Olivier Azam, 1 Nick Wood.
Replacements: 16 Scott Lawson, 17 Yann Thomas, 18 Pierre Capdevielle, 19 Will James, 20 Matt Cox, 21 Jordi Pasqualin, 22 Freddie Burns, 23 Lesley Vainikolo.
Saracens: 15 Nils Mordt, 14 David Strettle, 13 Kameli Ratuvou, 12 Brad Barritt, 11 James Short, 10 Owen Farrell, 9 Richard Wigglesworth, 8 Jackson Wray, 7 Andy Saull, 6 Justin Melck, 5 Hugh Vyvyan, 4 Steve Borthwick (c), 3 Carlos Nieto, 2 Schalk Brits, 1 Deon Carstens.
Replacements: 16 Jamie George, 17 Rhys Gill, 18 Petrus du Plessis, 19 Mouritz Botha, 20 Jacques Burger, 21 Neil de Kock, 22 Sam Stanley, 23 Noah Cato.
Date: Saturday, November 27
Referee: Sean Davey