Derek McInnes' side started the season with a point against Rangers.
Aberdeen have signed defender Tommie Hoban on a season-long loan from English Premier League side Watford.
The 24-year-old has made almost 60 appearances for the Hornets since making his debut eight years ago.
Hoban, who represented the Republic of Ireland at under-21 level, spent time on loan at Blackburn Rovers during the 2016-17 season.
Hoban, who will wear the number 28, goes straight into the Dons squad for tomorrow’s Europa League match against Burnley at Pittodrie.
Dons manager Derek McInnes said: “Tommie is a player we had in last week and thankfully we managed to get the deal resurrected.
“First and foremost he’s an excellent defender and it’s well known that we’ve been in the market for another defender and to get a player of his quality from Watford is a great piece of business.
“Although he can play anywhere in the defence, centre-back is his preferred position.”
Aberdeen boost squad ahead of Europa League tie by completing loan deal for Watford defender
