Sam Allardyce has said Everton are on the brink of signing Cenk Tosun and hope to register the Turkey international in time for Friday’s FA Cup derby against Liverpool.

Everton have agreed a deal rising to £27m for the striker following talks with the Besiktas president, Fikret Orman, in London on Wednesday. Tosun has still to finalise a four-and-a-half year contract at Goodison Park and pass a medical but, providing both are completed before midday on Friday, the 26-year-old could feature in the Everton squad for the third-round tie at Anfield.

“It is just personal terms now, the final stage,” Allardyce said on Thursday. “After long negotiations we are nearly there. He might even be registered before the FA Cup but securing the player is the most important thing because a lack of goals has been our biggest area of concern, and before I got here. With his pedigree and his age – we’ve not got many players in that elite age group in our squad – hopefully he will show he is good value for money.

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“If we get the transfer done and he comes and scores goals, it will be exceptional business. The club has searched high and low for a striker for a long time, since before I got here, and he was the one we focused on. He wants to come here.”

The Everton manager is wary of risking Tosun’s fitness in the derby but admits his inclusion may be necessary against Liverpool due to the well-documented weaknesses in the team’s attack this season.

“Possibly, but it all depends on his overall fitness,” said Allardyce. “We wouldn’t want to damage him just because it’s the FA Cup. There is a lot of mental energy that you burn when you are waiting for these moves to happen and the assessment will come from the medical and fitness staff. We just want to get the deal done first. There is a huge pressure on the lad and we hope he can handle it.”

Allardyce, who expects to be without Michael Keane at Anfield due to a foot injury sustained in Monday’s defeat by Manchester United, admitted Everton’s belief that Ross Barkley will leave has not altered since his arrival as manager. He explained: “The club was resigned to losing Ross before I got here and I can’t see that changing.”

Chelsea, who Barkley turned down on transfer deadline day in the summer, are understood to have approached Everton on Thursday regarding a January move for the midfielder. The England international is available on a free transfer in the summer but the current Premier League champions are considering paying a fee now to secure his signature.

Earlier, the Besiktas president Orman confirmed the transfer of Tosun will be completed by the weekend.

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“Our interests and the player’s interests are important,” Orman said. “Cenk wants to join Everton. We want to do our part and we are working on a replacement.

“The era of buy, buy, buy is over. This is the era of buy, add value and sell. A final deal has not been reached yet but we have an agreement over the price. The end is near. The transfer will be wrapped up by the weekend.”