Disgraceful scenes of crowd disorder marred the Black Country derby and halted play for 34 minutes as Wolves beat West Brom in the FA Cup at the Hawthorns.
Fighting erupted close to the area in the stands reserved for the players' families, while missiles were also thrown by both sets of supporters following the visitors' second goal.
In the first match between the two sides in front of fans since 2012, Matheus Cunha's 78th-minute effort sealed the fourth round victory for Wolves, who had taken a first-half lead through Pedro Neto.
But the tension in the stands that had been simmering from before kick-off spilled over. Missiles were thrown into and from the visitors' section and before play could resume, fighting began at the other end of the field, leading to both teams leaving the field.
As stewards and police attempted to restore order, West Brom skipper Kyle Bartley was spotted emerging from that area of the ground with a child in his arms.
Another supporter was escorted out of a home area with blood streaming down his face as medical staff tried to stem a wound to the top of his head. A further fan was taken out of the stadium on a stretcher, although he appeared to be in good spirits.
Fans were told to return to their seats on numerous occasions and respective managers Carlos Corberan and Gary O'Neil were both seen talking to stadium officials and police representatives before the teams returned.
Wolves held their opponents at bay for the remaining 12 minutes to take their place in the last 16, although that was of secondary consequence on a day that brought back scenes many thought had disappeared from the English game and seem sure to bring a heavy punishment from the Football Association.
Trouble brewing all game
After waiting almost 12 years to witness this particular local derby in person, the respective sets of fans were ready to make a racket from well before kick-off.
With the teams back in the dressing room after the warm-up, West Brom's distinctive 'Boiler Man' mascot was virtually alone on the pitch when he came to the Wolves' supporters' attentions. Their reaction was not positive, which was in line with much of the chanting as the players came out and the game began.
Wolves defender Craig Dawson continued to be booed every time he touched the ball deep into the contest even though he gave the Baggies eight years' excellent service and remained with the club for a year after their relegation from the top flight in 2018.
Neto's goal was accompanied by two bright orange flares being thrown from the stand housing the 4,000-strong visiting contingent. Heads turning in the main stand indicated a Wolves presence that shouldn't have been there as security scurried to sort the situation out.
Water bottles thrown at Wolves midfielder Tommy Doyle as he went to take a second-half corner did not reflect well on the home supporters responsible.
Yet this, as needless as it was, hardly merited attention compared to what followed Cunha's goal.
Even as police tried to bring order to the situation, extra stewards were called into the affected areas and the stadium announcer appealed for supporters to return to their seats, the ferocious chanting continued.
Thankfully, once the game finally restarted, no supporters came on to the field at the final whistle.
Wolves end long wait for West Brom win
Wolves' victory was significant in the sense it was their first against West Brom in the FA Cup since 1949 and their first at the Hawthorns since 1996.
Although West Brom have dominated matches between these two teams, the infrequency of recent meetings has coincided with a huge swing in fortune.
While Wolves' Chinese ownership has delivered European football, renewed commitment and, through manager Gary O'Neil, virtual Premier League safety and financial stability, West Brom's future is less certain.
They borrowed more money from lenders MSD in November and given they are no longer in receipt of parachute payments, face an uncertain future if want-out owner Guochuan Lai cannot find a buyer.
Skipper Jed Wallace is one of their most saleable assets and it was the 29-year-old that Alex Mowatt was trying to find with the corner that led to Wolves' opener.
Wallace had dropped deep for the pre-planned set-piece, but Matt Doherty read it, intercepted and set Neto free.
The Portugal star wasn't smooth in his approach to the Baggies box but he eventually got enough control to send a low shot beyond Josh Griffiths.
Cunha's goal was also a breakaway, although by then the energy had gone out of West Brom's play.
Brandon Thomas-Asante wasted their best opportunity to equalise, blazing over from the edge of the area. Thomas-Asante and Wallace both also had early headers saved by Jose Sa before Neto had broken the deadlock.
West Brom are left to pursue their play-off push and Wolves can dream of doing to Wembley. But there was nothing uplifting about this horrible occasion.