Japan's first-ever win over Wales has consigned their beaten opponents to a one-place slip in the latest IRB World Rankings.
The Welsh drop from fifth to sixth in the rankings after the 8-23 defeat in hot and humid conditions at Tokyo's Chichibunomiya Stadium.
Former Australian Rugby League star Craig Wing scored a try against the depleted Wales side, who were shorn of 15 players involved in the British and Irish Lions tour.
Japan, hosts of the 2019 World Cup, stay in 15th but the two rating points accrued leave them just 0.38 behind world No.14, Fiji.
France profit from Wales' loss to go fifth despite their 0-30 reverse in Christchurch against New Zealand, who remain top of the list by almost three rating points.
One place adrift of Wales are Samoa, who have now won five of their last seven matches after beating Italy.
The 39-10 victory over the Italians in the four-nation tournament in South Africa leaves the islanders less than one rating point behind Wales, but their next opponents present a formidable challenge - the Springboks, a side the Samoans have never beaten.
South Africa accounted for Scotland 30-17 on Saturday, although the visitors did lead 17-6 at one stage in the second half. The sides stay second and 11th in the world respectively with unchanged points.
Meanwhile, Ireland maintained eighth place in the world with a 40-14 triumph over Canada in Toronto.
The result, played in front of a crowd of 20,396 - a record for a rugby match on Canadian soil - ended the home side's recent run of victories against Tonga, Fiji, USA and Russia but leaves them unchanged at 13th in the world.
Italy and Tonga, 10th and 12th before the weekend, swapped places thanks to Tonga's 18-9 win over USA in the Pacific Nations Cup.
The Tongans are now snapping at the heels of Argentina, who stay ninth in the world but with a reduced points total after England won 51-26 in Buenos Aires to complete a 2-0 series clean sweep.
IRB World Rankings - Top 20:
(Last week's position in brackets)
1(1) New Zealand 90.08
2(2) South Africa 86.94
3(3) Australia 86.87
4(4) England 85.76
5(6) France 81.59
6(5) Wales 81.36
7(7) Samoa 80.50
8(8) Ireland 79.58
9(9) Argentina 76.67
10(12) Tonga 76.17
11(11) Scotland 76.05
12(10) Italy 75.08
13(13) Canada 72.40
14(14) Fiji 71.29
15(15) Japan 70.91
16(16) Georgia 67.66
17(17) United States 67.14
18(18) Romania 66.18
19(19) Russia 61.99
20(20) Spain 60.44