LONDON (Reuters) - British sports and fashion retailer JD Sports, one of Nike's largest customers, gave the world's biggest sports brand by revenue a vote of confidence on Tuesday, with a senior executive saying it "will be just fine".

Late last month, Nike's shares plummeted after the group warned its sales would fall this year, hurt by faltering demand for its sneakers as consumers covet newer brands such as On and Hoka.

However, Mike Armstrong, FTSE 100-listed JD Sports's global managing director, said it would be wrong to write off Nike's prospects.

"Anybody that writes Nike off probably needs to go back and look at the history of Nike in the market place over the last sort of 30, 40 years. Nike will be just fine," he told reporters at JD's recently renovated flagship store in Westfield Stratford City, London.

JD also sells Adidas, On, Hoka and other sports brands.

"Over the years there's always been challenger brands ... That's just the nature of the industry that we're in. There's always going to be upstarts, there's always going to be incomers," said Armstrong.

JD's own share price is down 22% so far this year, hurt by a January profit warning and subdued first quarter trading in its home market.

Armstrong declined to comment on current trading ahead of an update expected next month.

JD sees the Stratford store, which has the highest turnover across its global portfolio of over 3,400 shops in 38 countries, as the blueprint for its global rollout of larger format stores.

Features include a stock of 30,000 boxes of shoes, a semi-automated conveyer system that can deliver a shoe box from storeroom to shop-floor in under 30 seconds, over 205 square metres of LED panelling, and handheld devices for all shop workers.

So far, about 70 JD stores globally have the same concept as Stratford, with close to 200 expected by the year end.

Last year, CEO Regis Schultz said JD would spend up to 3 billion pounds ($3.9 billion) to open as many as 1,750 stores over five years.

($1 = 0.7792 pounds)