Opportunity could be knocking for both Sunderland and Sheffield United as another Championship weekend hoves into view.

With the top two of Leeds United and Burnley otherwise engaged in the FA Cup fourth round, the Black Cats and Blades have the chance to take advantage.

In League One it is all about jostling for a play-off spot with Birmingham City and Wycombe Wanderers also looking for cup glory, while Wrexham twiddle their thumbs as Leyton Orient take on Manchester City in the competition.

Walsall's stumbles have suddenly got a few pundits reviewing their 'give them the title now' declarations in League Two where a familiar face returned to management this week, but let's start our preview in the Championship.

Sunderland and Sheffield United used the January window to stoke the fires of their respective promotion bids and have the chance to heap the pressure on Burnley and Leeds.

The Black Cats turned striker Wilson Isidor's loan from Zenit St Petersburg into a permanent move along with the deadline-day loan acquisition of Liverpool forward Jayden Danns.

Those two signings, plus Enzo Le Fee's loan from Roma, means boss Regis Le Bris appears to have all his bases covered for the final 16 games of the season.

That run starts at home to Watford on Saturday lunchtime with the Hornets on a three-game losing streak, but still within one win of the top six. Victory for Sunderland could move them into third, above Sheffield United and level on points with second-placed Burnley.

As for Sheffield United, a win over Portsmouth would push them back into the top two and only a couple of points behind Leeds.

The Blades 1-0 win at Derby last weekend steadied the ship after their shock home defeat by Hull City.

Pompey visit Bramall Lane more in hope than expectation with six league defeats in a row on the road, albeit a home draw with Burnley last Saturday keeps them three points clear of trouble.

Outside of Leeds and Sunderland no-one has more points from their past six Championship games than Norwich City, whose four wins have helped carry them into eighth place - with a chance to break into the top six this weekend.

Norwich have been helped by the return from injury of Josh Sargent, who has three goals in their past two outings. They will also have the division's top marksman, Borja Sainz, back from a six-game ban from Tuesday.

Not that Norwich fans will expect to miss Sainz for Saturday's game at home to Derby County. The third-from-bottom Rams are looking to avoid a club record-equalling eighth successive league defeat.

Such is the jam of sides chasing the top six, tenth-placed Sheffield Wednesday could also enter the play-off places at the expense of their opponents West Bromwich Albion this weekend.

The Owls had a relatively quiet transfer window but retaining Shea Charles on loan might prove their best piece of business.

Tony Mowbray's return to The Hawthorns has produced a win and two defeats so far, but they will be happy to be at home with deadline-day signing Adam Armstrong set to make his debut.

It is all about jostling for play-off positions in League One where the top three might not be in action, but four of the top six in the current form table are.

Charlton have six wins from their past nine games and would already be in the play-off spots if they had not given up a 2-0 lead at Blackpool last weekend.

A mid-season run of two wins from 10 outings had a few Addicks fans shuffling uncomfortably in their seats, but all is well again as they welcome in-form Stevenage who have recorded impressive wins over Barnsley, Wrexham and Exeter City in their past three matches.

Stockport County went four games without a win over the festive period but four wins in a row have got them back on track and sitting in fourth place ahead of a home meeting with Barnsley. The loss of top scorer Louie Barry does not seem to be affecting County too much at the moment.

Now, did Huddersfield Town 'win' the transfer window in League One?

The signings of forwards Joe Taylor and Dion Charles, along with Wolves midfielder Tawanda Chirewa, certainly caught the eye, but the Terriers have lost three on the bounce.

Visiting West Yorkshire this weekend are eighth-placed Reading, who sold top scorer Sam Smith to Wrexham last week.

So, Charlton, Stevenage and Stockport are three of the four in-form sides playing in League One this weekend, but who are the fourth?

If you answered Burton Albion, then you are correct.

Eleven points from five matches has lifted them to within sight of safety from a seemingly impossible situation. Jon Dadi Bodvarsson has scored four goals in his past four appearances and the Brewers will hope he can continue that form at home to Blackpool.

Bolton Wanderers started life under new boss Steven Schumacher with defeat by Reading last week and his first home game is against struggling Crawley Town.

Carlisle United can be accused of many things by their supporters but being dull is not one of them.

This week, the EFL's bottom side sacked head coach Mike Williamson on transfer-deadline day having allowed him to sign 11 players during the window.

So, five points from safety and having lost five of their past six games, the Cumbrians have turned to Mark Hughes to try to prevent relegation into the National League.

As the club's third permanent boss this season, the Wales and Manchester United legend's first game in charge is away at play-off hopefuls Grimsby Town on Saturday.

So, are Walsall about to blow it at the top of League Two?

Probably not, but two defeats and a last-ditch draw against Salford mean the Saddlers juggernaut might need a top-up at the service station before hitting the road again.

Their next stop is against a Colchester side who have taken 10 points from four games, sparking hopes of a late play-off push in north Essex.

AFC Wimbledon take a seven-match unbeaten run to Accrington Stanley, while Port Vale, without a defeat in their past five, have a lunchtime date at Swindon Town.

Two other promotion chasers take on relegation-threatened sides as Notts County host Morecambe and Salford City face Tranmere Rovers.

Harrogate Town visit Bradford City with the Bantams having won only two of their nine EFL meetings against their less heralded opponents.