Chelsea were the biggest spenders of a record-breaking January transfer window for Premier League clubs while relegation-threatened teams also splashed the cash on a frenetic final day.

Leaders Arsenal took a more measured approach in strengthening a number of key areas, but Manchester United and struggling Liverpool -- two clubs whose owners are seeking fresh outside investment -- were relatively quiet.

AFP Sport looks at some of the talking points after £815 million ($1 billion) was spent by the English top flight last month.

Arsenal reinforce core

The Gunners are five points clear at the top of the Premier League with a game in hand -- but have they done enough in January to get over the line?

Manager Mikel Arteta wanted highly-rated Ukraine winger Mykhailo Mudryk and Brighton's Moises Caicedo to turbo-charge his push for the club's first league title since 2004.

But Arsenal could not match Chelsea's bid for Mudryk while Brighton rebuffed approaches for their prized midfielder.

Instead, they have added Leandro Trossard, also from Brighton, and Italy international Jorginho, who was snapped up from Chelsea, along with Polish defender Jakub Kiwior.

Trossard adds quality and depth to Arteta's options in wide areas, where Gabriel Martinelli and Bukayo Saka have excelled this season.

Midfielder Jorginho, 31, brings experience and trophy-winning nous after notable success at club and international level.

Arsenal's title bid may also have been aided by Manchester City's lack of activity.

The defending champions boast enviable strength in depth but added only Argentine youngster Maximo Perrone and shipped out one of their key players in recent seasons as Joao Cancelo joined Bayern Munich on loan.

Strugglers splash the cash

Just six points separate Nottingham Forest in 13th from bottom-of-the-table Southampton and the race is well and truly on to escape the relegation trapdoor.

Bournemouth, currently 18th in the table, were the second biggest spenders last month.

Four of the five bottom clubs -- West Ham, Wolves, Bournemouth, and Southampton -- splashed out around £175 million.

Bournemouth made six signings, bringing in Ukraine defender Illia Zabarnyi from Dynamo Kyiv and Ivory Coast midfielder Hamed Traore in the final hours of the window on Tuesday.

Southampton broke their transfer record, snapping up Rennes and Ghana winger Kamaldeen Sulemana for a fee that could reportedly rise to more than £24 million.

The group of clubs hovering just above the bottom five also spent big, with Forest adding yet more new names -- three on the final day -- in an ongoing revolution at the newly-promoted club.

Leeds broke their transfer record in signing Hoffenheim attacker Georginio Rutter, while Leicester brought in Australia defender Harry Souttar from Stoke.

But second-bottom Everton did not make a single January signing to further anger an unhappy fanbase.

Man Utd and Liverpool quiet

Liverpool were quick out of the blocks, agreeing a sizeable deal for Dutch international forward Cody Gakpo in late December as Jurgen Klopp sought to boost his forward line.

But last year's quadruple-chasers failed to do any more business despite their faltering form.

The decision not to reinforce an ageing midfield has raised eyebrows with Liverpool ninth in the table and out of both domestic cup competitions.

Uncertainty over the club's ownership is one of the reasons given for Liverpool's lack of activity and the same can be said of Manchester United.

The Red Devils did not buy a single player to strengthen their push for a top-four place but boosted their options with three loan signings.

United responded quickly to an ankle injury suffered by Christian Eriksen to bring in Marcel Sabitzer from Bayern Munich on deadline day.

Manager Erik ten Hag signed Netherlands forward Wout Weghorst, giving him the option of a tall target man to add bite to his attack, and Jack Butland's arrival added depth to the goalkeeping options.