By Editor Wayne Veysey | Former Evening Standard, Press Association and Goal chief correspondent with 17 years experience of breaking big stories, including exclusives like this

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Arsenal have opened preliminary contract discussions with Alexis Sanchez, Football Insider sources understand.

The first meeting has taken place between Gunners chiefs and the Chilean forward in the hope of reaching an agreement in the coming months.

A senior Arsenal source has told Football Insider that discussions are centred around a five-and-a-half-year agreement that will run until 2021 and could be worth a staggering £51.5million.

Sanchez has been a huge success at Emirates Stadium since his £32million move from Barcelona in the summer of 2014.

He has recently returned to action following a two month lay-off and is set to be in the team that faces Bournemouth in the Premier League on Sunday afternoon.

Sanchez wants pay parity with Mesut Ozil, who, as revealed by Football Insiderhas already agreed in principle a deal that will elevate his basic salary by £50,000-a-week to £180,000-a-week.

Gunner stay: Arsenal are keen to tie Ozil down to new deal

Gunner stay: Arsenal are keen to tie Ozil down to new deal

Sanchez currently earns £130,000-a-week, which makes him the club’s equal top earner along with Ozil. Only manager Arsene Wenger earns more than Arsenal’s two most expensive ever signings.

The Londoners are keen to tie down first-teamers aged under 30 to long-term contracts and the Sanchez contract situation is the latest on their radar.

The Chilean signed a four-year deal when he joined and it is due to expire in the summer of 2018.