Liverpool edged out West Bromwich Albion at the Hawthorns to tighten their grip on fourth place.

A first-half header from Roberto Firmino was enough to seal the win and keep Everton at arm's length, though Manchester United could cut their lead with a win against Chelsea today.

The Brazilian forward nodded home after James Milner's flick-on to hand the Reds the lead.

And despite late desperation, and throwing Ben Foster forward, West Brom couldn't get level.

But what did we learn?

1. Liverpool squeeze out a win - a skill in itself

Klopp and Liverpool have eked out consecutive narrow wins (Getty)

Klopp has been asked for weeks if his Liverpool side have what it takes to “win ugly”. And not without good cause after sloppy defeats against the likes of Burnley, Bournemouth and Swansea this season.

But, just as they did last weekend at Stoke, the Reds showed here they do have the stomach for a fight when needed.

The Hawthorns on grizzly Sunday afternoon is not where you want to be going with the likes of Manchester United and rivals Everton breathing down your neck for the top four. But Klopp’s men stood up to all that was thrown at them and won with a goal from a set-piece, something very un-Liverpool-like of late.

The Reds have infamously struggled against the likes of the Baggies all season long but did the job here to get what could prove to be an invaluable three points.

2. West Brom on the beach?

Tony Pulis' side have somewhat dipped since securing survival (Getty)

Since hitting that magical 40-point mark, West Bromwich Albion's mind has clearly been elsewhere.

The Baggies were only four points off a European place but, since then, have conspired to win just four of a possible 21 points to fall away from Everton and the top six.

It won't affect Albion much in terms of relegation or even prize money if they cough up a couple of league positions, but it will cement the narrative that Tony Pulis has a 'ceiling' as a manager. Just when it appeared he might be nicely set to kick on and challenge the more established elite, his team just stopped picking up points.

3. Albion undone at set pieces

Tony Pulis' side did well to hold out Liverpool in open play, their narrow back four stifling and frustrating the Reds' rotation of attackers with relative ease.

But the Welshman will be fuming at how his side switched off on the brink of half-time, conceding a set-piece goal that was eminently preventable.

5ft 9in James Milner won the headed flick-on from a low free-kick and the 5ft 11in Roberto Firmino nodded home from close range.

With three central defenders on the field and some height elsewhere, it's not a goal Pulis would expect his team to concede and, if his past exploits are anything to go by, these Baggies players will be getting shredded for it in their next training session - if not sooner.

Not that it will fix this result. Albion defended throughout this game exactly as they would have wanted to pre-match - it was only a second of sloppiness that undid that good work and cost them points.

4. Mignolet comes up big when it matters... at last

Simon Mignolet has so often been a figure of fun at Liverpool. Clanger after clanger left the Reds’ goalkeeping situation a revolving door for much of the season. But the Belgian has done the business when needed in back to back weeks now. Against Stoke he saved his side’s bacon with a wonderful stop and this week he, after barely being tested for the majority of the game, was on hand to deny Matt Phillips when it looked like the Baggies man may nick a late equaliser when put through.

5. Liverpool strengthen their grip on fourth place

Klopp knows his side likely control their own destiny (Getty)

There is a certain animosity between Liverpool and Chelsea but you can bet your bottom ruble that they'll be cheering on Antonio Conte's men at Old Trafford as they head back to Merseyside.

Jose Mourinho was insistent on Thursday night that his team remain in the driving seat, with [now three] games in hand on the Reds.

But any points dropped at Old Trafford against the champions-elect would mean Liverpool control their own fate.