West Brom's difficult week off the pitch culminated in disappointing fashion on it as Alan Pardew's side crashed out of the FA Cup fifth round with a 2-1 defeat to fellow Premier League strugglers Southampton.
Pardew's preparations for Saturday's encounter had been marred by the actions of Jonny Evans, Gareth Barry, Jake Livermore and Boaz Myhill, who were reportedly interviewed by Spanish police after they allegedly stole a taxi during the club's training camp in Barcelona.
Evans and Barry nevertheless started at the Hawthorns, but the hosts were up against it from the 11th minute when Wesley Hoedt capitalised on dreadful defending to volley home from James Ward-Prowse's corner.
Jay Rodriguez's early opportunity set the tone for a much-improved second half for the Baggies, but West Brom found Alex McCarthy in superb form before Dusan Tadic doubled Southampton's tally on the counter.
Salomon Rondon's extraordinary strike set up a grandstand finish, Ahmed Hegazi denied an equaliser by both McCarthy and the crossbar.
A leveller was not forthcoming for West Brom, however, as Southampton held firm to secure their spot in the last eight.
Evans, stripped of the captaincy following his alleged indiscretions in Barcelona, was the first to go close for either side, McCarthy making a fine stop to keep out the defender's looping header.
West Brom were a goal down two minutes later as Hoedt, unmarked from Ward-Prowse's corner, side-footed a cushioned effort into the bottom-left corner.
Southampton could smell blood, and only a last-ditch clearance from Craig Dawson prevented Pierre-Emile Hojbjerg doubling their advantage.
James McClean finally offered some threat going the other way, the Republic of Ireland international's long-range effort flashing inches wide of the upright.
Evans' inclusion was justified prior to half-time, as the Northern Irishman got across to make a vital challenge on Tadic following good work from Nathan Redmond.
Rodriguez could have made his mark against his former club just after the restart, but McCarthy reacted brilliantly to tip the striker's effort wide.
Southampton's goalkeeper was at his best again from the resulting corner, somehow keeping out Dawson's close-range header.
But West Brom's rally was dealt a blow in the 56th minute, with Guido Carrillo teeing up Tadic, who kept his composure to loft a tidy finish over Ben Foster.
The visitors' two-goal cushion was cut short after just two minutes, however, as Rondon hammered in a venomous volley that gave McCarthy no chance.
Hegazi saw his effort clawed off the line by McCarthy as West Brom piled on the pressure, while Matty Phillips should have done better with a strike from the edge of Southampton's box.
Egypt defender Hegazi did get the better of McCarthy with 10 minutes remaining, but the woodwork came to Southampton's rescue before Ryan Bertrand cleared Rondon's effort off the line from the rebound as the Saints managed to claim just a fourth away win of the campaign.
KEY OPTA STATS
- Southampton have reached the quarter-finals of the FA Cup for the first time since 2004-05.
- Since beating Liverpool in the last round of the FA Cup, West Brom have lost all four of their matches, conceding at least twice in each match.
- Southampton won twice away from home in the same calendar month against an opponent for the first time in their entire history.
- Hoedt scored his first Southampton goal and his first since netting in a 7-3 win for Lazio against Sampdoria in May 2017.
- Ward-Prowse has had a hand in five goals in his last five appearances against West Brom in all competitions (three goals, two assists).
- Since his debut for West Brom in August 2015, Rondon has scored 25 goals in all competitions – 15 more than any other Baggies player in that time.