Why South African-born Duhan van der Merwe is a deeply compelling selection for the British & Irish Lions tour

As far as in-form wingers go, recently qualified Scottish international Duhan van der Merwe has to be at the top of the list after an astounding introduction to test rugby over the last year.

The 25-year-old South African-born wing has long been one of the Pro14's most destructive attacking players, and that ability translated directly to the international game when he made his debut for Scotland last Autumn.

Van der Merwe immediately made his mark, making the most line breaks and second most defenders beaten in the Autumn Nations Cup, albeit with just three appearances. He added to his two tries from November with five in four Six Nations games, the most in the tournament.

Again, he was top of the list when it came to defenders beaten, equal first with his captain Stuart Hogg with 14 and second on the list of line breaks.

If you are looking for a powerful, strong ball-carrying wrecking ball that asks for two or three man tackles on every touch, how can you look past Van der Merwe for a left wing berth?

Four years ago, Warren Gatland went with a back three combination of Liam Williams at fullback, Anthony Watson on the right wing and Elliot Daly on the left for all three tests in New Zealand. Speed and aerial skills were valued attributes, and will surely be high on the criteria list again in South Africa.

Although Daly was the first choice left wing selection in that series, the multi-positional England back has not been in career-best form of late and, of the three, presents the most likely to lose his standing.

The insatiable form of Scotland fullback Stuart Hogg could also see Williams squeezed to the left wing, a role he has performed recently for Wales with Leigh Halfpenny back in the 15 jumper.

Although, of all the available options above, none have the power game of Van der Merwe, whose 1.93m, 103kg frame would be an asset against a defensively strong Springboks side that crushed opponents in Japan with a vice-like hold over the gain line.

Scotland deployed their newest wing as a first-receiving carry option frequently off set-piece throughout the Six Nations, allowing Van der Merwe to plough a destructive path over smaller flyhalves and midfielders and give his side a great platform.

If you can get first phase gain line carries from your wingers, you don't need them as much from your 12. That would allow the Lions to run a dual-flyhalf system again at 10 and 12 as they did with Jonathan Sexton and Owen Farrell on the last tour.

If Gatland has a desire to continue the 10-12 playmaking axis, the hard first phase momentum has to come from somewhere.

Granted, the loose forwards can be used on short lineouts and it was centre Jonathan Davies who filled that role in New Zealand to preserve Sexton and Farrell for use on latter phases.

The great Davies is a question mark at the moment. The 33-year-old would be on his third Lions tour and recently moved to inside centre in favour of George North at 13 after missing the early rounds with injury in Wales' latest Six Nations triumph. Whether Davies can play the role that the Lions need at outside centre is unknown.

If you were weighing up who is more likely to smash over the gain line against the Springboks with more ferocity, Van der Merwe is far more likely to generate post-contact metres than the 1.85m, 104kg Davies at this stage of their respective careers.

The selection of either player is not mutually exclusive either, Davies may well be the first choice 13 and Van der Merwe could take some of the carrying load off him.

As a pure finisher, having a power athlete like Van der Merwe on the left flank gives the Lions a flexible 'margin of error' in attack going right to left. You don't need to execute plays perfectly to create space for him, as long as you give him time and short distances to the goal line.

He creates his own space and routinely will win one-on-ones or one-on-twos when all that is required is five-to-10 metres to score.

Against England in the Six Nations, he finished with little room by cutting inside Daly and barging through the tackles of Farrell and Mark Wilson where a lesser-bodied wing would have come up with nothing.

On the final play against France, he cut inside Damian Penaud and dove over with no regard for the next French defender trying to tackle him.

On the Springboks right side is Cheslin Kolbe, standing at 1.71m and 74kg, while Willie le Roux - who, at 1.86m and 90kg, is another small operator compared to Van der Merwe - will be at fullback.

Both can defend and both can tackle, but they needn't just tackle Van der Merwe. That won't be enough.

They need to stop his momentum dead in his tracks, something neither will be able to from close range purely based on physics. Van der Merwe will score in contact over both of them with enough time to wind up.

Having this 'margin of error' in attack will be a real strong point for the Lions during a pressure-cooker series where scoring opportunities are infrequent and the chances to attack from inside the 22 may be counted on one hand.

Le Roux, having played two seasons in the largely defenceless Japan Top League, will need to prepare his body for the Lions and putting Van der Merwe in his path will be the ultimate way the Lions can put him under the spotlight.

If the Springboks are still running their aggressive defensive tactics, Kolbe will be trying to shut play down by jamming in one man, leaving Van der Merwe free altogether. It would be a dangerous gambit to leave the adopted Scotsman uncovered.

It would perhaps force the Springboks to re-think their defensive strategy if the Lions can cause significant damage in the first test through their own South African juggernaut.

The attacking side of the equation presents a compelling case for Van der Merwe's inclusion.

On the other side of the coin, aerial prowess and reliability under the high ball is a must. While Williams is a self-proclaimed 'professional bomb diffuser', Daly has always had question marks in this area of the game but provides a left-footed kicking option on the flank.

Van der Merwe hasn't been tested a lot under the high ball or in kick coverage at test level, but in the rain in Paris against France, he handled himself well.

If the Lions play a two-deep backfield with their 10 and 15 anyway, it would keep Van der Merwe in the front line where he can be tasked with checking runners to create clean jumps for his teammates. As a big-bodied wing, he can re-direct traffic with smart lines.

When he is on the far side wing in exit situations, he can become a third man in the backfield as a counter-attack option on the opposite side from where Faf de Klerk's box kicks land.

In contact, he managed to lift his subpar 68 percent tackle completion from the Autumn Nations Cup to a resounding 82 percent in the Six Nations.

For Van der Merwe himself, it would be a deeply spiritual journey to return to South Africa as a Lion and play against the Springboks, adding a powerful emotive aspect to his selection.

What's more, he deserves it on merit based on recent form, as he's proved he possesses strength and power unrivalled by any wing in the Six Nations. What he has to offer can suit specific Lions game plans that we have seen in the past.

Duhan van der Merwe can be the edge that gives the Lions an advantage, a South African born to play against South Africa.