Wales secured a vital win against nearest rivals Japan in their bid to remain in the top 14 of the World Rugby Sevens Series.
Richie Pugh's side went into the penultimate round of the series in 14th spot, three points ahead of Japan.
But tries from captain Luke Treharne, Afon Bagshaw and Joe Goodchild saw Wales secure a 17-0 win in the challenge trophy quarter-final.
They face Scotland in the semi-final later on Sunday.
Wales had lost to Australia and series leaders the United States before victory over Spain in Saturday's pool matches.
Wales squad: Luke Treharne (capt), Owen Jenkins, Ethan Davies, Cai Devine, Afon Bagshaw, Joe Jenkins, Joe Goodchild, George Gasson, Cameron Lewis, Dafydd Smith, Reuben Morgan-Williams, Ben Cambriani, Tom Rogers, Morgan Williams.