Emery considers selling more Arsenal stars.
Emery made six signings during the English transfer window, including Chelsea defender David Luiz and Celtic full-back Kieran Tierney.
But Alex Iwobi left for Everton, Carl Jenkinson moved to Nottingham Forest and former captain Laurent Koscielny departed acrimoniously for Bordeaux in recent days.
Koscielny’s fellow centre-back Shkodran Mustafi and midfielder Mohamed Elneny have also been linked with moves away from the Emirates Stadium.
And Gunner’s boss Emery hinted there could be more departures with Italian, German, French and Spanish teams able to add to their squads for several weeks.
“I am really delighted with our work. The club did everything to get the best players to help us and to make our squad stronger,” Emery told reporters on Friday.
“As you can understand, we are changing players at the last moment and also with Laurent Koscielny, he was the first captain, and he left us five days ago.
“Also, we have had other players come in. Now we have the squad and we have finished the transfer market, but it’s still open in other countries.
“Unfortunately, we can achieve the last moment finishing yesterday with some players but now in the next 25 days we could lose some players.”
Arsenal start their Premier League campaign at Newcastle on Sunday, with the distinct possibility that none of their six new players will be in the starting line-up.
Tierney is nursing a groin problem and Real Madrid loanee Dani Ceballos took a heavy challenge to his ankle in last week’s friendly defeat by Barcelona.
Luiz and club-record signing Nicolas Pepe are both short of full fitness.
“We are going to start Sunday with players who I am very convinced can perform now at 100 per cent,” Emery added.
“For some, that’s impossible for them to achieve that performance for us because they arrived later or started training with us after injuries.”
– Lacazette injury worry –
Alexandre Lacazette could also miss out as he continues his recovery from an ankle issue suffered in the Emirates Cup loss to Lyon.
Arsenal missed out on the top four by a single point and lost the Europa League final to Chelsea in Emery’s first season.
But following their busy transfer window, former Paris Saint-Germain boss Emery is now keen to push on and secure a return to the Champions League.
“The Premier League is the best competition in the world,” he said. “We are going to work and be with a big challenge to compete in this competition to find the top four.
“The Premier League is the most important competition and we are going to start on Sunday and it is going to give us the regularity and consistency in 38 matches.
“It’s the first way for us to achieve our targets and objectives to be in the top four, but we know it’s going to be difficult.”