London, Sep 8: English Premier League side Chelsea have stepped up their quest to rope in Spanish football side Atletico Madrid's star forward Antoine Griezmann.

Days after the transfer window shut shop, work is already in motion for potentially a second-successive world transfer record, according to a report in English paper The Telegraph on Wednesday.

Manchester United have also reportedly set their sights on securing the services of their star midfielder Paul Pogba's France team-mate.

Griezmann though is adamant he would only leave if Atletico coach Diego Simeone departed.

Chelsea is reportedly also willing to grant their striker Diego Costa his wish to return to Atletico -- rather than trigger Griezmann's 84 million pounds ($112 million) release clause -- in order to sweeten the deal.

IANS