After a difficult week off the pitch, West Brom were knocked out of the FA Cup at the fifth-round stage after a 2-1 loss at home to Southampton.
Alan Pardew handed starting berths to Jonny Evans and Gareth Barry, two of the players who were forced to apologise after breaking a club curfew during West Brom's mid-winter break in Barcelona this week, but Evans was stripped of the captain's armband.
Southampton took an 11th-minute lead when Wesley Hoedt ghosted in unmarked to volley home from a corner, before Dusan Tadic put Saints within touching distance of the last eight with a well-taken goal in the 58th minute.
A stunning volley from Salomon Rondon pulled a goal back two minutes later, but Saints held on to book a first FA Cup quarter-final spot since 2005.
West Brom: Foster (6), Evans (6), McAuley (6), Dawson (6), Hegazi (6), Barry (5), Krychowiak (7), Phillips (5), McClean (6), Rondon (7), Rodriguez (5).
Subs: Brunt (6), Burke (N/A), Field (N/A)
Southampton: McCarthy (8), Cédric (7), Stephens (7), Hoedt (7), Bertrand (6), Lemina (7), Højbjerg (6), Ward-Prowse (6), Tadic (7), Redmond (6), Carrillo (6).
Subs: Sims (N/A), Romeu (6), Gabbiadini (6).
Man of the match: Alex McCarthy
The events of the week seemed to have taken their toll on the West Brom players as they struggled to find any rhythm, and soon enough they were behind.
James Ward-Prowse whipped a corner into the middle, two West Brom defenders missed it, and Hoedt was on hand, in acres of space, to steer a volley into the bottom corner.
Saints could have gone two goals to the good, but were denied by a smart Ben Foster stop after Pierre-Emile Hojbjerg had steered the ball towards goal.
Down the other end, West Brom were lumping plenty of balls into the box, but Jack Stephens and Hoedt were dealing with such service easily. The closest the hosts came to an equaliser in the first half was via the boot of James McClean, but his fierce strike sailed wide.
There were two changes from the West Brom side beaten at Chelsea. Kieran Gibbs and Daniel Sturridge made way for Gareth McAuley and Jay Rodriguez.The big news was that McAuley skippered the side and not Evans, who appeared to have been stripped of the captaincy. One Saints change from the defeat to Liverpool, with Oriol Romeu dropping to the bench and Nathan Redmond coming into the side.
The action intensified after the break, with Alex McCarthy called into action, making several stops to keep his side in front, the best of which was a fine save to tip Grzegorz Krychowiak's deflected strike around the post.
Those saves proved vital, as Tadic doubled Saints' lead. The ball into him was pinpoint from Guido Carrillo, Tadic controlled, benefited from a fortunate bounce, before clipping the ball over the onrushing Foster into the net.
However, in the blink of an eye and West Brom were back in it. Krychowiak searched out Rondon with the long ball, the West Brom striker let the ball drop over his shoulder, before rifling the volley into the net from fully 25 yards.
McCarthy again clawed the ball out from a corner as West Brom pressed for a leveller, but the closest the hosts came to restoring parity came late on, as Ahmed Hegazi's looping effort came down off the crossbar.
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.
Wesley Hoedt scored his first Southampton goal and his first since netting in a 7-3 win for Lazio against Sampdoria in May 2017.
James Ward-Prowse has had a hand in five goals in his last five appearances against West Brom in all competitions (three goals, two assists).
Alan Pardew: "I felt I needed to make a little bit of a statement about the events. I was far from happy over them and made Gareth captain today. I've got to stay faithful to the players and give them a chance to remedy the situation. Gareth Barry was okay today but I thought Jonny was very good actually in the circumstances."
Mauricio Pellegrino: "I think the win is important for many reasons. The first one is the belief of the team to improve. I think the spirit of the team was really good. It is something we were talking about last week, even in difficult situations like at the end. We were competing well and were focused. In a physical battle they are really strong and also we gave an opportunity to other players who have not played so much in the past month."
Man of the match - Alex McCarthy
For large swathes of the match, McCarthy was idle, with West Brom struggling to create many chances. However, in the second half, McCarthy made three fine stops in quick succession to ensure his side stayed in front. The fact he stayed so alert, after being untested for so long, deserves great acclaim.
The Premier League returns next week, with West Brom hosting Huddersfield, while Southampton travel to Burnley.