Lloyd Williams produced the clever kick that set up scrumhalf Gareth Davies for the converted try which secured the famous win.
The latest rankings list released by World Rugby also shows a drop of three places for England from third to sixth.
Wales have now lost five injured players from their original World Cup squad, with Williams and Amos joining Leigh Halfpenny, Rhys Webb and Cory Allen.
“Even going in to the game, people knew that we had a few world-class players missing”, said assistant coach Shaun Edwards after the remarkable Welsh win.
“I feel cheeky taking man-of-the-match. It should be shared by all of the boys today”, said 25-year-old Biggar.
“I don’t think we will be resting too many players [against Fiji], but obviously that is down to the boss [Gatland]”. So we’ll be putting a pretty strong team out against Fiji. He expects a better determination of their status on Monday, a rest day for Wales.
Farrell added: “It is disappointing from someone who is not in the environment”. Wales finished that game with a flyhalf at fullback, a wing at centre, and a scrumhalf on the wing.
It left Gatland pondering just who he could call on with Wales facing Fiji at the Millennium Stadium in Cardiff on Thursday.
“It could easily have ended up a draw as well”.
But the England coach has piled the pressure on his flops by admitting Saturday’s showdown with Australia is now their World Cup final.
Scarlets midfielder Williams (knee) and Newport Gwent Dragons back Amos (shoulder) went off during the second half of Wales’ 28-25 Pool A victory over England at Twickenham on Saturday.
Dan Biggar kicked Wales to a stunning 28-25 comeback victory over World Cup hosts England on Saturday night as South Africa got their campaign back on course with an emphatic 46-6 triumph over Samoa.
Wales have collected nine points from a possible 10 in Pool A despite injuries providing one setback after another, and North has underlined the squad’s determination to remain firmly on a quarter-final course.
Back supported England head coach Stuart Lancaster’s much-discussed changes in team selection for the Wales game, but questioned the replacements made in the second half when the home side were leading.
But there was still time for England to win a late penalty – only for captain Chris Robshaw to decline the chance of three points for a successful kick to tie the scores – and go for a try from a line-out. Our discipline was very poor and when it counts and the game is on the line, we weren’t on it. Against France in Paris in the warm-up game our discipline in the first half was shambolic.
“They all dug deep and they have all worked so hard”.