Match ends, West Bromwich Albion 3, Swansea City 1.
Salomon Rondon's first Premier League hat-trick helped West Brom secure their third successive home league victory and plunge Swansea deeper into the relegation mire in the process.
The visitors were the better team in the first half, dominating possession against an under-par West Brom, but the hosts sprang back to form after the break.
Rondon's goals - all headers - came in a devastating 13-minute period early in the second half and highlighted the defensive frailties which have contributed to Swansea's poor season.
The visitors did reduce the deficit late on as Wayne Routledge finished a fine move started by substitutes Modou Barrow and Borja Baston, but it was mere consolation.
Victory for West Brom moves them to seventh, four points adrift of Manchester United in sixth, while Swansea remain in the relegation zone, three points from safety.
Baggies transformed after the break
West Brom fans, accustomed to better at home this season from a team who had lost just three of their last 11 league games prior to this match, were clearly frustrated before the break as they watched the Baggies lose possession too easily.
But, despite being below their best, the hosts did engineer the best chances of the first half.
Rondon drew a fine save from Lukasz Fabianski, while Nacer Chadli thought he had headed home Chris Brunt's free-kick, only for the goal to be disallowed with Jonas Olsson deemed offside.
Those missed chances mattered little as the Baggies transformed their fortunes after the break by playing at high tempo and pressing with urgency.
They were also helped by a Swansea defence that repeatedly failed to deal with crosses into the box.
Rondon headed home Matt Phillips' inswinging free-kick to open the scoring and, 11 minutes later, was again unmarked as the £12m striker converted Brunt's deep cross towards the far post.
The Venezuelan completed his hat-trick in the 63rd minute, with Brunt again the provider as the striker found the top-right corner.
The 27-year-old becomes only the second player to score a hat-trick of headers in the Premier League, with former Everton striker Duncan Ferguson the only other to do so, against Bolton in 1997.
Swansea's defensive weakness on show
The visitors were the more assured and composed in possession in the first half, replicating the pattern of play which eased them to a 3-0 win over relegation rivals Sunderland on Saturday.
Bob Bradley's men enjoyed over 60% of possession in the opening 45 minutes, but did not truly test Ben Foster in West Brom's goal, which proved to be their downfall.
Indeed, the closest they came to scoring was through Brunt as the Baggies defender nearly swept Jefferson Montero's cross into his own net.
But the ease with which Swansea quickly crumbled after the break magnified the team's weakness - they have now conceded 15 goals in five league games away from home under manager Bradley.
The Welsh side, second best in the aerial duels, stood back as West Brom attacked and paid the price.
Bradley, who replaced Francesco Guidolin as manager on 3 October, admitted his team conceded the second "too quickly" and said Swansea need to "turn things around fast".
Man of the match - Salomon Rondon (West Brom)
What they said
West Brom boss Tony Pulis: "We played 24 hours later [last weekend] than Swansea had and, in the first half, we looked laboured.
"I'm pleased for the group. I thought in the first 20 minutes of the second half - that's where the game was won and we played like we can play.
"We say a few things [at half-time] and sometimes you have to say a few things. It was more to do with the fact we had to step up. The main players in the team stepped it up, and that was the important for us. They were three fantastic headers. We're pleased for him and the group. We really had to dig deep and oil the engine."
Swansea boss Bob Bradley: "Defence is an area where we have to improve. If we could have kept in the game at 1-0, started to play some passes... but all too many times this season we give up the second goal all too quickly and that happened again.
"Even when you play well, you don't always take the lead. On both the second and third goals, we didn't move out very quickly, and they were allowed deep into the box.
"I thought the first half was solid. Now the key is being able to play for 90 minutes and handle different situations in the game."
Rondon steals the show
- Rondon has scored 16 goals in the Premier League since the start of last season - 11 more than any other Baggies player. (James Morrison is on five).
- The striker's hat-trick was also the quickest by a Baggies player in the Premier League (13 minutes), overtaking the record set by Rob Earnshaw in March 2005 against Charlton (16 minutes).
- Chris Brunt - who assisted twice in this game - has 42 Premier League assists for West Brom, 19 more than any other player for the club.
- The Baggies have scored 10 goals in their last three home Premier League games - more than they managed in their previous 10 games at the Hawthorns in the competition (8).
- Wayne Routledge has scored four Premier League goals against West Brom - double the amount he's scored against any other team.
West Brom host Manchester United on Saturday, 17 December, in what manager Pulis describes as an "unbelievably hard game", while Swansea take on Middlesbrough on Saturday in their second of three games in eight days.
- 22ChadliSubstituted forMcCleanat 71'minutes
- 7MorrisonSubstituted forGardnerat 77'minutes
- 9RondónSubstituted forRobson-Kanuat 85'minutes
- 7BrittonSubstituted forCorkat 72'minutes
- 23G Sigurdsson
- 20MonteroSubstituted forBarrowat 64'minutes
- 9LlorenteSubstituted forBastónat 72'minutes
- 5van der Hoorn
- Michael Oliver
- Shots on Target
Second Half ends, West Bromwich Albion 3, Swansea City 1.
Attempt missed. Jack Cork (Swansea City) left footed shot from the centre of the box misses to the right. Assisted by Modou Barrow.
Offside, West Bromwich Albion. Gareth McAuley tries a through ball, but James McClean is caught offside.
Foul by Jay Fulton (Swansea City).
James McClean (West Bromwich Albion) wins a free kick in the attacking half.
Corner, Swansea City. Conceded by Jonas Olsson.
Attempt blocked. Alfie Mawson (Swansea City) header from the centre of the box is blocked. Assisted by Gylfi Sigurdsson with a cross.
Corner, Swansea City. Conceded by Claudio Yacob.
Offside, Swansea City. Jordi Amat tries a through ball, but Modou Barrow is caught offside.
Jay Fulton (Swansea City) wins a free kick in the defensive half.
Foul by Craig Gardner (West Bromwich Albion).
Foul by Jack Cork (Swansea City).
Hal Robson-Kanu (West Bromwich Albion) wins a free kick in the defensive half.
Attempt missed. Borja Bastón (Swansea City) right footed shot from the right side of the six yard box misses to the left. Assisted by Gylfi Sigurdsson with a cross.
Substitution, West Bromwich Albion. Hal Robson-Kanu replaces Salomón Rondón.
Corner, Swansea City. Conceded by Claudio Yacob.
Modou Barrow (Swansea City) wins a free kick in the defensive half.
Foul by Nyom (West Bromwich Albion).
Goal! West Bromwich Albion 3, Swansea City 1. Wayne Routledge (Swansea City) right footed shot from the centre of the box to the bottom left corner.