England's preparations for the World Cup continued to unravel after captain Owen Farrell was sent off in a 19-17 victory secured through a late George Ford penalty.
At one point during the final quarter Steve Borthwick's men were reduced to 12 men when Farrell - whose yellow card for a dangerous tackle on Taine Basham was upgraded to a red by the bunker - followed the sin-binned Freddie Steward and Ellis Genge into the stands.
England's brainless final quarter saw a 9-3 lead overtaken by a penalty try and swashbuckling Tomos Williams touch-down as an otherwise lifeless encounter exploded into life the moment Steward took Josh Adams out in the air in the 60th minute.
A fourth successive defeat and slump to ninth in the world rankings beckoned, but England rallied bravely and even with three players off the pitch they claimed a maul try scored by Maro Itoje before Ford landed the winning penalty with three minutes left.
Farrell now faces a ban that could see him miss the World Cup opener against Argentina on September 9, with his recent three-match suspension for the same offence in January sure to count against him.
Jack Van Poortvliet sustained an ankle injury to leave England sweating on his fitness, while Dewi Lake, Taine Plumtree and Basham emerged as concerns for Wales, who ultimately ran out of steam.
There was little to signpost the action to come in a dull first half that saw Farrell reward England's solid start with a penalty.
The one-way traffic was eventually broken up by a 50-22 that gave the visitors a short-range line-out, but England defended the ensuing maul well and a rare chance was gone.
Two returning stars making their first appearances under Borthwick made pleasing starts, with Billy Vunipola barrelling into Wales up front and Elliot Daly showing his athleticism in attack.
Slowly, Wales were clawing their way into the game but time and again were hampered by unforced errors as the match meandered along a stop-start path, unable to shake off its training ground feel.
Lake hobbled off to add to Warren Gatland's injury concerns at hooker but England were reeling soon after Van Poortvliet departed following an accidental collision and Henry Arundell was sent to the sin-bin for not retreating 10 yards.
The half finished with a Red Rose assault on the whitewash but in all-too familiar scenes they were unable to break through and had to settle for a second Farrell penalty.
Tommy Reffell was sin-binned for not releasing an opponent and over went another Farrell penalty, but Wales were finally off the mark when Owen Williams landed three points.
Plumtree was the next to exit nursing an injury as play continued to be marred by error after error, with another promising spell of England pressure petering out.
Genge came on to win his 50th cap and was then shown a yellow card for collapsing a scrum, but worse was to come when Steward followed him into the sin-bin for taking Adams out in the air.
Adams was close to the line and Steward's subsequent tackle on Liam Williams prevented a certain score, so a penalty try was awarded.
Somehow England were the the next to cross through a maul and when Ford landed a late penalty their against-the-odds escape act was complete.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here