Arsenal manager Arsene Wenger believes Manchester City's "spectacular" transfer window proves he is in for his toughest campaign yet.
City have splashed out an estimated £217million on the likes of Bernardo Silva, Ederson, Kyle Walker, Danilo and Benjamin Mendy ahead of the 2017-18 season.
Arsenal open the new Premier League campaign on Friday with a home match against 2015-16 champions Leicester City.
Ahead of the first game, Wenger was asked if this would be his most difficult season and responded in agreement, praising the work his side's main rivals have done with their transfers.
"Yes, because look at what City have done," he said.
"They have been quite spectacular in the transfer market, Manchester United as well.
"And it's not finished - Chelsea have bought [Alvaro] Morata and have not lost [Diego] Costa yet, and they will certainly buy more. In the middle of the transfer market it's difficult to predict [the season].
"At the moment the most active have been United, City and Liverpool a bit."
While other sides have had significant squad overhauls, Arsenal have only brought in Sead Kolasinac and Alexandre Lacazette, although the latter did cost EUR60m.
Despite a lack of new faces, Wenger insists the club remain ready to do more business - but reiterated they need to cut numbers as a priority.
"We are still open," he said. "But of course at the moment I have currently 33 players and it is very difficult to manage on a daily basis such a high number."
But Wenger stressed Arsenal were never on the brink of signing Leicester playmaker Riyad Mahrez, a rumoured target who will now come up against them at the Emirates Stadium.
"We were never close," said the Frenchman. "I rate him as a player but we have similar types with Alex Iwobi, Jack Wilshere back, Mesut Ozil - we have plenty of the same type of players."