The key players facing contract uncertainty if season goes beyond June 30

Here, the PA news agency looks at some of the highest-profile players who could be affected.

David Silva, Manchester City

Season stats: 28 appearances, three goals, eight assists

The Spanish playmaker's memorable decade in Manchester is coming to an end this summer, with him seeking to add a third FA Cup and possibly a first Champions League title to his 11 major trophies with the club – could his ride into the sunset be delayed?

Olivier Giroud, Chelsea

Season stats: 13 appearances, three goals

Sidelined by the early-season form of Tammy Abraham, the veteran France striker has deputised effectively as the young Englishman has struggled with injury. Scored in Premier League wins over Tottenham and Everton and the UEFA Super Cup against Liverpool.

Willian, Chelsea

Season stats: 37 appearances, seven goals, six assists

The Brazil winger, 31, remains a key man in a largely inexperienced squad under Frank Lampard and his influence would be sorely missed should any end-of-season complications arise. Fellow winger Pedro may be less of a priority but should both be left in limbo, the need to get Christian Pulisic back to full fitness will become more acute.

Jan Vertonghen, Tottenham

26 appearances, two goals, four clean sheets

Toby Alderweireld re-signed in January but his fellow Belgium defender is yet to follow. Scored a late winner against Wolves in the league and also netted in the FA Cup exit to Norwich, while he reached 300 games for the club on Boxing Day against Brighton. Rising defensive star Japhet Tanganga's own expiring deal features an optional extension which the club are sure to trigger.

Adam Lallana, Liverpool

Season stats: 22 appearances, one goal, two assists

The midfielder has returned from an injury-hit spell to make several contributions, notably scoring the late equaliser against Manchester United in October which extended Liverpool's unbeaten league run. The Reds could also have to negotiate a change of kit supplier, with Nike due to take over the contract from New Balance on July 1.

Matty Longstaff, Newcastle

Season stats: 11 appearances, three goals

The teenager has made quite an impact after joining older brother Sean in the Magpies' midfield, scoring in both meetings with Manchester United – including on his Premier League debut – as well as the FA Cup win over Rochdale. Manager Steve Bruce last month said of his contract: "It's a concern for us – I hope we can get that tied up."

Ryan Fraser, Bournemouth

Season stats: 32 appearances, one goal, four assists

Still only 26, the Scotland winger has not enjoyed his most productive season but the Cherries will still be desperate to get a new deal sorted. Their relegation struggle provides a further layer of complication.