Cape Town - Ever noticed England's Owen Farrell doing his trademark locked finger 'JJ' gesture after every successful shot at goal or try scored - and wondered why?

Wonder no longer.

According to The Sun website, England flyhalf-cum-centre Farrell dedicates every point of his career at international and club level for Saracens to 11-year-old Jack Johnson, who suffers from Duchenne muscular dystrophy (DMD), a genetic disorder characterised by progressive muscle degeneration and weakness.

At present there are around 2 500 DMD sufferers in the United Kingdom, but Farrell's help in raising awareness has provided funds for vital research into treatments.

Farrell’s 'JJ' sign refers to the Joining Jack charity established by the boy’s parents when he was struck down by the life-limiting condition in 2011 when he was just three years old.

Jack's father Andy Johnson is a former team-mate of Farrell's father Andy from their days at the Wigan Warriors rugby league side.

Owen Farrell is expected to play a crucial role in Saturday's Rugby World Cup final against the Springboks in Yokohama.

With victory, Farrell will become just the eighth captain to lift the coveted Webb Ellis Cup.

But not if Siya Kolisi and his Springboks team-mates have anything to say about it...

Kick-off is at 11:00 SA time.

Teams:

England

15 Elliot Daly, 14 Anthony Watson, 13 Manu Tuilagi, 12 Owen Farrell (captain), 11 Jonny May, 10 George Ford, 9 Ben Youngs, 8 Billy Vunipola, 7 Sam Underhill, 6 Tom Curry, 5 Courtney Lawes, 4 Maro Itoje, 3 Kyle Sinckler, 2 Jamie George, 1 Mako Vunipola

Substitutes: 16 Luke Cowan-Dickie, 17 Joe Marler, 18 Dan Cole, 19 George Kruis, 20 Mark Wilson, 21 Ben Spencer, 22 Henry Slade, 23 Jonathan Joseph

South Africa

15 Willie le Roux, 14 Cheslin Kolbe, 13 Lukhanyo Am, 12 Damian de Allende, 11 Makazole Mapimpi, 10 Handre Pollard, 9 Faf de Klerk, 8 Duane Vermeulen, 7 Pieter-Steph du Toit, 6 Siya Kolisi (captain), 5 Lood de Jager, 4 Eben Etzebeth, 3 Frans Malherbe, 2 Bongi Mbonambi, 1 Tendai Mtawarira

Substitutes: 16 Malcolm Marx, 17 Steven Kitshoff, 18 Vincent Koch, 19 RG Snyman, 20 Franco Mostert, 21 Francois Louw, 22 Herschel Jantjies, 23 Frans Steyn