Lawrence OkoyeIt was only in March last year that Lawrence Okoye was charging over the try-line to score at Twickenham, a couple of opponents clinging forlornly to his mountainous frame. At 6ft 5in and 20st, with a No 11 shirt on his back, and a flick of hair at the front of his otherwise shaven head, he was already known as "the schoolboy Lomu".

The teenage double of the giant New Zealand wing, who famously trampled all over Tony Underwood, Mike Catt and Co in the semi-final of the 1995 Rugby World Cup, was a member of the academy set-up at London Irish, as well as being a try-scoring hero for the victorious Whitgift School – the Croydon alma mater of Danny Cipriani – in the final of the English Under-18s cup at the national HQ of the oval-ball game. Fourteen months on, however, Okoye is making his mark in a different sporting field. A very big mark.

At the Surrey county track-and-field championships at Kingston upon Thames last Saturday, in his first competition as a senior athlete, the 19-year-old threw the discus 63.25 metres. With one fell swoop, he had achieved the B standard selection mark for the 2012 Olympics, 63m. At the Loughborough International meeting at the Paula Radcliffe Stadium on Sunday, the traditional curtain-raiser to the top-level track-and-field season in Britain, Okoye will be gunning for the Olympic A standard, 65m.

From scoring tries at Twickenham, the Jonah Lomu lookalike has switched his sights to throwing for glory as a member of Team GB at the Olympic Stadium in Stratford, east London, next year. It has been quite a turnaround for the multi-talented young man from Waddon, south London. And for British athletics, at the start of this pre-home Olympic season, Okoye has been quite an acquisition.

He was a known quantity in the sport last summer, having shown his raw talent by finishing sixth at the World Junior Championships in Moncton, Canada. It was then that the Croydon Harrier decided to make the switch from rugby union – and a winter of full-time training, under the direction of the experienced throws coach John Hillier, has propelled the Croydon Harrier to the cusp of a major breakthrough in his new sporting life.

"It's incredible the way things have worked out," Okoye reflected. "I've gone from strength to strength since I met John. At the start of the winter he said to me: "Lawrence, you're going to throw 65m in the summer." At first I thought: 'Nah, I can't do that.' But as the winter went on I realised that I could. I fully expect to throw 65m now.

"I'm targeting a medal at the European Under-23 Championships [in Ostrava in the Czech Republic in July] and a GB vest at the World Championships [in Deagu, South Korea in August]. That should stand me in good stead for next year, for Olympic time.

"I've changed my lifestyle to do this. I was going to go to university after finishing school last summer, to study law at Oxford. I decided to defer for two years so that I could train for the Olympics and it's paid dividends already."

In the 14 months since he scored his try at Twickenham, the former "schoolboy Lomu" has grown bigger than the 6ft 5in, 19st original was in his All Black prime. Okoye now stands 6ft 6in tall and tips the scales at 20st 6lb. As well as being strong enough to heave the discus 63.25m, he is quick enough to break 11sec for 100m, a combination of power and pace that would make him a potent force in any rugby team.

"I do miss rugby a lot," Okoye confessed. "There are not many better feelings than scoring tries. I don't know if I'll go back to it after 2012. If I do really well at the Olympics it would be foolish of me to stop throwing the discus."