The former rugby league wing left five Gauteng tacklers for dead, and coming as it did just seven minutes after Austin Healey's superb opening try, it ripped the game from the South Africans' grasp in the most dramatic fashion immaginable.
Bentley struck on 67 minutes, picking up the ball fully 60 metres out, beating two tackles on the wide right before curving inside and giving three more defenders the slip before finishing off under the post. Gauteng breathed fire in the final ten but with the Lions' back row of Tim Rodber, Rob Wainwright and Neil Back giving everything in defence, they were restricted to an injury time try by Andre Vos, their blind side flanker.
Dawie Du Toit made an embarrassing foul-up of his first penalty shot after Tim Rodber and Neil Back killed the ball on the floor but made no mistake after five minutes when John Bentley was caught well offside near his own posts.
Mike Catt squared it almost immediately from distance but the Lions were still under the cosh - and in more ways than one. Will Greenwood's try- saving tackle on Joe Gillingham in the right corner was quickly followed by a humdinger of a punch by Chris Rossouw, the Boks' World Cup-winning hooker from 1995, on Barry Williams, his opposite number. Williams had chosen to use Bruce Thorne as a dormat at a line-out, but it was Rossouw who received the ear-bashing from Mr Henning.
While Catt struggled to adjust his radar - he hit the left-hand post twice in the opening half - du Toit settled into his rhythm with two relatively straightforward shots to give Gauteng a 9-3 advantage at the break. But the Lions finished the first 40 minutes with a spell of encouraging territorial advantage, and had Tony Underwood not stumbled inside the home 22 after excellent work from Back, Rob Wainwright and Catt, an opening try would have been his for the taking.
That strong finish to the first period galvanised the Lions and with Back buzzing around like an entire swarm of bees, Gauteng were on their uppers from the restart. Catt was short and wide with an early penalty effort but Jeremy Guscott contributed one of his dangerous chip-and-chase raids to win an attacking scrum - a valuable platform wasted when Back knocked on in the tackle five metres short.
With Jeremy Davidson the dominant force at the line-out, Guscott was finding the sort of space that makes him a threat to any defence in the world. Sadly, an uncharacteristic missed tackle on Gillingham allowed Gauteng to turn the tables and it needed two of Tony Underwood's bravest tackles to repulse them, one on Johan Roux in the right corner and a second on Rossouw in the left.
After the stern and unforgiving close-quarter battle before the interval, the game was now alive with pace and adventure. Nick Beal's hack through would have resulted in a try but for brilliant defensive work from Hendriks and Andre Vos while in turn, Guscott made amends for his earlier slip by pulling the rampaging Piet Krause to the floor inches from the Lions' line.
Then, on the hour, came the breakthrough. Bentley used his strength to protect Lions' possession close to the right touch line and with help from Williams and Rodber, Greenwood squeezed through the smallest of holes into the Gauteng 22, fed Austin Healey with a sublime pass out of the tackle and turned in jubilation to see the scrum-half sprinter outstrip the cover on his way to the right corner. Neil Jenkins, on for the injured Underwood, sank the most awkward of conversions and the Lions were in front for the first time.
Gauteng: D du Toit; J Gillingham, J van der Waht, H le Roux, P Hendriks; L van Rensburg, J Roux; R Grau, C Rossouw (J Dalton, 52), K van Greuning, K Wiese (capt), B Thorne, A Vos, W Brosnihan, P Krause.
BRITISH ISLES: N Beal (Northampton and England); J Bentley (Newcastle and England), J Guscott (Bath and England), W Greenwood (Leicester), T Underwood (Newcastle and England); M Catt (Bath and England), A Healey (Leicester and England); T Smith (Watsonians and Scotland), B Williams (Richmond and Wales), P Wallace (Saracens and Ireland), N Redman (Bath and England), J Davidson (London Irish and Ireland), R Wainwright (Watsonians and Scotland) T Rodber (Northampton and England, capt) N Back (Leicester and England). Replacements: N Jenkins (Pontypridd and Wales) for Underwood, 55.
Referee: T Henning (Northern Transvaal).