The 80-1 outsiders had knocked out Sevens heavyweights New Zealand and Samoa to reach their first final on a day of major shocks in Dubai.

Wales, who lost to Argentina in the pool stages, opened a 12-7 half-time lead with tries from Richie Pugh and Tal Selley before Pumas drew level.

But Aled Thomas stole down the blindside to seal the Melrose Cup for Wales with the decisive try.

Wales only returned to the full International Rugby Board Sevens circuit in 2005 and had never got beyond the semi-finals stages of any tournament.

Wales came into the tournament ranked 11th in the world and only qualified for the last eight on points difference.

But they set the tone on a remarkable finals day in Dubai with a 15-14 victory over New Zealand, their second victory over the Kiwis inside a month.

England crashed out in the quarter-finals to Samoa, while defending champions Fiji were beaten by Kenya and Argentina defeated South Africa.

Wales then beat Samoa 19-12 in the semi-finals to set up an unlikely rematch with the Pumas.

Wales led 12-7 at half-time courtesy of Pugh’s arcing run to the corner and a brilliant solo try from Selley, who straighten and dummied his way through the Argentina defensive line.

Aled Brew preserved that advantage to the interval with some committed last-ditch defence.

Neither side was willing to chance their arm too early in the second half and relied heavily on tactical kicking.

But Thomas made the decisive breakthrough with sniping down the blindside from the base of a ruck to win the match and confirm Wales as world champions.