Everton manager Ronald Koeman is expecting the whole of the Premier League to be very busy between now and the end of the transfer window and says every club is still looking to bolster their respective squads with fresh additions.

Koeman's men have spent around £140m (€153.4m, $180.1m) on a host of new signings this summer but their transfer business is far from over, with a striker and central defender still on the Dutchman's agenda.

Everton were linked with a move for Chelsea outcast Diego Costa, with recent reports claiming that Koeman is considering a loan deal for the fiery Spain international.

Costa has made his desire to return to Atletico Madrid very clear in recent weeks, and Los Colchoneros have reportedly agreed an initial €45m (£41.1m, $52.9m) fee for the 28-year-old forward, who is refusing to return to Chelsea's training complex.

The former Southampton boss is very pleased with the signings Everton have already made and is prepared to remain patient in his attempts to recruit more targets - he was made to play the waiting game earlier this summer when the Toffees were locked in talks with Swansea City over Gylfi Sigurdsson.

Koeman knows drawn out negotiations are very much part and parcel of the transfer market and suggested some surprising moves may materialise in the dying embers of the window, with a host of clubs desperate for new arrivals.

"We did good business, and I think it's normal, it doesn't always happen like that at the start of the Premier League," Koeman told the Liverpool Echo. "You already have five, six, seven players in. And if you like to bring more players in, maybe it takes some more time for that.

"OK, anyway, we were really patient in the situation with Gylfi. 'It's close, it's close, it's still close...' Of course, it would have been better if it had been done one week ago.

"But finally, we have the agreement and everybody is happy about that. I think it's normal. But look through the rest of the teams. Everybody's still looking to sign new players, even [Mauricio] Pochettino from Tottenham mentioned three or four players and it's still two weeks from the end of the transfer window.

"We will see more changes in all of the teams and it is still unpredictable what will happen until the end of August in the transfer window."

Koeman has welcomed seven new first-team players to Everton this summer but identified former Swansea talisman Sigurdsson as the key addition to his set-up at Goodison Park.

Koeman spoke publicly about Everton's pursuit of the esteemed Icelandic international on a number of occasions but his concerns over the deal were regularly allayed by Toffees chairman Bill Kenwright, who constantly assured the Barcelona legend that Sigurdsson would be playing in blue this season.

"Yeah, but from the beginning, when I heard from the board, when I heard from the chairman Bill [Kenwright], he was always so calm," said Koeman, who is preparing Everton for their trip to Manchester City. "He said: 'I will do the deal but we need to be patient.' And of course I understand it's business.

"It's a big transfer. You don't do these kind of transfers in two days. Sometimes it takes longer than you like. But OK, anyway, I was quite comfortable that finally we would do this deal, because it's really important, and everybody was patient in this situation."

Ronald Koeman
Koeman is anticipating a surprising end to the transfer window. Getty Images