Wales blew the Six Nations wide open with an epic 21-13 victory over England.
Late tries for Cory Hill, after a monumental 30-phase goal-line assault, and Josh Adams at the death secured a national record 12th successive victory.
England were leading 13-9 after a first-half Tom Curry try and looked set to make it three wins in a row before the hosts turned the match, and possibly the championship, with a relentless attack that sent Hill over 12 minutes from time.
Winger Adams then caught a high kick in the corner to settle it and send the Principality Stadium into raptures, bringing back memories of 2013 when England arrived in Cardiff seeking a Grand Slam but were sent packing 30-3.
Saturday's game was a different beast, with momentum swings and nail-biting tension, but the outcome produced the same outpouring of emotion.
Wales top the standings on 12 points, with England second on 10, though, thanks to their earlier bonus points and with home games against Italy and Scotland to come, they are still well-placed to win the title.
Wales, who visit Scotland then host Ireland on the final day, are also in the hunt for their first title 2013.
France, who beat Scotland 27-10 earlier on Saturday, have six, with the Scots on five. Defending champions Ireland, on four points, visit bottom side Italy on Sunday with renewed interest.
In a tight first half, England continued with their kicking policy while Wales tried to keep the ball in hand.
England's defence was immense, though, with Kyle Sinckler, Courtney Lawes, Mark Wilson and Curry tackling anything that moved to ensure the absent Make Vunipola and Maro Itoje were not missed.
The atmosphere, as expected, was electric but the thousands of England fans who had found tickets made their presence felt with "Swing Low" reverberating around the ground, before being drowned out by a cascade of boos.
It was locked at 3-3 after a penalty apiece before England struck in the 27th minute. Lawes stripped the ball from Justin Tipuric and Curry peeled off the ruck almost unseen to charge over.
Farrell converted and England's supremely organised and, these days, disciplined defence meant Wales's best efforts came to nought and the visitors led 10-3 at the break.
Wales, though, chipped away with two more Gareth Anscombe penalties to get within a point on the hour mark as the home fans cranked up the volume with the match, and potentially the Six Nations championship, on a knife-edge.
England struck next as Curry forced a penalty that Farrell slotted over and it looked as if Eddie Jones's side would march on following their impressive wins over Ireland and France.
But there followed a monumental passage of play as the Welsh pack hammered at the line relentlessly for more than 30 phases. England matched them hit for hit but eventually buckled as the hosts went wide for Hill the charge over.
Replacement five-eighth Dan Biggar converted and hammered the final nail in the coffin with a spiralling kick for Adams to catch and scramble over.
Wales's 12th successive win surpassed the previous best run set from 1907-1910 and few victories could have been celebrated more vociferously.