Arsenal dropped points following a 1-1 draw at home to Brighton after Declan Rice was shown the first red card of his career.
Brighton have completed a swoop for Fenerbahce's Turkey international full-back Ferdi Kadioglu for an undisclosed fee.
Brighton have signed Danish midfielder Matt O'Riley on a five-year contract from Celtic.
Manager Erik ten Hag says Manchester United need to show a more ruthless side after being beaten 2-1 by Brighton in the Premier League on Saturday.
Brighton boss Fabian Hurzeler has backed Georginio Rutter to make a big impact, as he considers the possibility of giving him his debut against Manchester United.
Brighton have reportedly activated Leeds forward Georginio Rutter's release clause of £40million.