Premier League clubs across London are gearing up for a flurry of activity in the final hours of Deadline Day as Arsenal, Chelsea and Tottenham look to improve their squads before time runs out.

The latter hope to continue strengthening Ange Postecoglou's ranks following the signing of centre-back Kevin Danso from RC Lens on loan with an option to make the switch permanent for a fee in the region of £21million.

Spurs also look set to win the tightly-contested race for the signature of Bayern Munich winger Mathys Tel with the 19-year-old reportedly Tottenham-bound for the remainder of the season. Chelsea could also be busy in the final few hours of the window with a number of deals still in the pipeline.

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Across North London, even after the Gunners' 5-1 win over champions Manchester City. Aston Villa rejected an approach valued at £60million to convince Ollie Watkins to move to the Emirates stadium - it is not yet known as to whether Arteta will return for Watkins or pursue other options before Monday's 11pm deadline.

However, if any of the aforementioned sides were to seal a last minute squad addition they may need a transfer deal sheet to get their business over the line. But what are they and how do they work?

As mentioned, the window closes at 11pm UK time. To confirm that a deal for a player has been agreed before the market closes, a transfer deal sheet must be filled out to allow for more time to thrash out any last minute details. The concept was introduced to the in 2008.

Due to the hectic nature of , some clubs have mere minutes to fill out the document and ensure the move can take place.

Once submitted, the clubs have an additional two hours to get any potential signing over the line if the sheets are completed correctly. Failure to dot the I's and cross the T's before the two-hour extension renders any deal invalid.

The information on the sheet itself is simple - signalling which player will be making the switch, the clubs they are moving to and from, the transfer or loan fee and any other potential add-ons.

In order to register a player, clubs have to send the Premier League all documents relating to the transfer, including the contract, the transfer agreement, permission to work in the UK, if required, international clearance if transferring from abroad as well as any transfer levy that may apply.

According to the Premier League, officials from the competition will approach clubs as the deadline approaches to ask whether they are planning to complete any business so that the Premier League's Football Operations and Regulatory departments are prepared.

The league's office is staffed up until the 11pm deadline should any queries from clubs arrive.