Manchester United manager Ruben Amorim has warned Arsenal striker Viktor Gyökeres that he faces a battle to maintain his form now he has moved to the Premier League.
Gyökeres was prolific under Amorim at Sporting CP, netting 66 goals in 68 games under the boss before his departure to United midway through last season. That form convinced Arsenal to spend €73.5 million (£63.4 million, $86 million) to bring Gyökeres to the Emirates Stadium this summer.
