Aberdeen manager Derek McInnes believes Hearts secured arguably Scottish football's best player when they re-signed Steven Naismith.
Naismith signed a four-year contract on Thursday and could feature in his team's Ladbrokes Premiership opener at Pittodrie on Sunday.
The 32-year-old hit 14 goals last season despite undergoing two knee operations and was instrumental in Hearts' flying early-season form.
McInnes said on his club's official website: "We know Hearts are a capable team. A lot has been said about them but I think they have signed very well.
"I think the four main signings they have made are very good. Conor Washington has a good pedigree, Jamie Walker did well there before, Craig Halkett is a player I have huge admiration for and I think he will do fantastically well there, and Steven Naismith will give them a real boost because he was arguably the best player in Scotland last season before he got his injury. He was very influential.
"There is no doubt Hearts will be up there again and will want to come up and start the season strongly and get a positive result.
"So we think Hearts will be a tough opponent but we are glad we are at home and we are not having to travel."
Aberdeen warmed up for their league opener with a 5-0 Europa League win over Chikhura Sachkhere on Thursday.
"They will be rubbing their hands with the amount of energy we expended on Thursday and that is a concern," McInnes said.
"We have dealt with the European games and now it is important we try regroup. We took players off on Thursday night with Sunday in mind.
"Hopefully we will have a few players back so we can freshen the team up in the right areas. We kept players back with Sunday in mind.
"We will try and get as fresh a team as possible out there to deal with what will be a tough game but will be an exciting game.
"Sometimes when you play in Europe the excitement and anticipation of the first league game proper can sometimes get diluted but for us that is not the case.
"Everyone who was there on Thursday night will be back on Sunday and hopefully a few more supporters. Hearts will bring a strong crowd as well so the game will generate a fantastic atmosphere and hopefully we will deliver a performance that helps us get the three points."