Does January transfer spending achieve league success? We've crunched last season's numbers to find out…
Last year, five of the big six clubs made a net profit from winter transfers, while Arsenal barely recorded a net spend with £100,000 on youngster Cohen Brammall.
In terms of results, Liverpool suffered a torrid January in 2017, their title bid derailing with three draws and one defeat in the league - and just one win out of nine in all competitions.
However, despite the dip in form, Reds boss Jurgen Klopp failed to add to his squad at all during the window. That inactivity may have contributed to a league-high points-per-game drop of 0.26 during the second half of the season.
This term, Klopp has acted quickly to bolster his much-criticised defence and secured the signature of summer target Virgil van Dijk for £75m from Southampton.
Last season, Premier League clubs made a combined net profit of £32m from winter transfer dealings in 2017 - but clubs at the lower end of the table bucked the trend.
Crystal Palace suffered a 2-0 defeat at Arsenal on New Year's Day last year and sat 17th in the Premier League table - just two points ahead of Sunderland and the drop zone.
However, Sam Allardyce had replaced Alan Pardew at the helm on December 23 and splashed a league-high £39m on Patrick van Aanholt, Luka Milivojevic and Jeffrey Schlupp - in addition to loaning Mamadou Sakho - to secure survival and finish 14th.
Swansea were rock bottom at this stage last year, with 12 points from 19 games, but a £13m spree on Tom Carroll, Martin Olsson, Luciano Narsingh and a swap deal for Jordan Ayew helped the Swans retain top-flight status, rising five places to 15th and increase their points-per-game ratio by a league-high 0.45.
But Palace and Swansea were the only two clubs to have been among the biggest spenders and make notable progress in the league come May. Everton also spent heavily and improved their points-per-game ratio significantly to retain seventh place.
Like this season, Burnley were flying high in 11th last year and spent £18m on Robbie Brady and Ashley Westwood - but suffered a league-high drop of five places by the end of the season.
Middlesbrough also hovered above the relegation places in 16th and had only scored 17 goals from 19 fixtures. But a £20m January spree on strikers Patrick Bamford and Rudy Gestede - in addition to midfielder Adlene Guedioura - proved ineffective with only 12 goals scored during the second half of the season, as the club suffered relegation.
Sunderland recorded a net profit from January dealings, with David Moyes offloading Van Aanholt for £14m and only signing his former Everton players Darron Gibson and Bryan Oviedo for £4.5m each - but dropped two places to finish bottom of the table.
Watford sat in 13th on New Year's Day last year, and also boasted profit from the winter window with a £24m surplus - but the Hornets crashed four places to narrowly avoid the drop in May.
Typically, clubs fighting for survival are more active during the winter window, while Crystal Palace and Swansea both proved there is potential for considerable improvement from making effective signings.
However, winter spending does not always translate into league improvement, as Burnley and Middlesbrough showed last year.
But, after a summer of record-breaking transfer fees and price inflation, clubs fighting for survival could struggle to recruit effectively within their budgets and may source more players on loan.