Welsh pressure eventually told as they completed a five-point victory over Uruguay in a 54-9 mauling. It came at a price however as hat-trick hero Cory Allen was one of a trio of injuries along with Liam Williams and Dan Lydiate.
Having been written off thanks to the unfortunate pre-tournament loss of star men Leigh Halfpenny and Rhys Webb, Wales sent a warning shot to Pool A rivals England and Australia with an emphatic win on home soil.
The Reds dominated in all areas of the game and stormed to a 28-9 half time lead thanks to a 23 minute hat-trick from Cardiff Blues centre Allen. Fly-half Rhys Priestland made up the rest of the halves scoring, converting all four of the Welsh tries.
Heavyweight prop Samson Lee crashed over for the first in response to a 6-0 Uruguay lead through the boot of Felipe Berchesi.
Once the first try went over, the floodgates opened as Wales secured a vital bonus points win with the first 40.
Full-back Liam Williams was replaced on 36 minutes to compound further injury woes to Warren Gatland.
After the interval, Hallam Amos touched down to become the youngest try scorer at this World Cup and get the Welsh boys up and running in the second half.
But just five minutes later the unthinkable happened. Man of the match Cory Allen limped off the pitch to send Wales’s campaign into further disarray.
Further tries from Justin Tipuric and a Gareth Davies brace added gloss to the scoreline, but a further injury to Liam Williams could spell disaster for their long-term prospects in this competition.
The South Americans offered little in the way of hope to suggest that they could pose a threat to this Pool although Berchesi was stable enough from the tee to at least ensure that his side was not beaten to nill.
A bruising encounter proved so costly for the home side, and replacements may need to be called up to fill the gaps of an ever depleting squad.
Wales: Liam Williams (Matthew Morgan 36); Alex Cuthbert, Cory Allen (Lloyd Williams 55), Scott Williams, Hallam Amos; Rhys Priestland, Gareth Davies; Paul James (Aaron Jarvis 32), Scott Baldwin (Ken Owens 63), Samson Lee (Thomas Francis 40), Luke Charteris (Dominic Day 47), Jake Ball, Sam Warburton (Dan Lydiate 59), Justin Tipuric, James King (Ross Moriarty 47).
Uruguay: Alejo Corral (Mateo Sanguinetti 77); Carlos Arboleya (German Kessler 77), Mario Sagario (Oscar Duran 72), Santiago Vilaseca, Jorge Zerbino (Franco Lamanna 59); Juan Manuel Gaminara, Matias Beer (Juan De Freitas 59); Alejandro Nieto, Agustin Ormaechea (Alejo Duran 74), Felipe Berchesi, Rodrigo Silva, Andres Vilaseca (Agustin Alonso 74), Joaquin Prada (Francisco Bulanti 75), Santiago Gibernau, Gaston Meres