Tottenham are in talks with Benfica over a loan deal for striker Carlos Vinicius.
The potential agreement is likely to include an option to buy the Brazilian for around £36m.
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Vinicius joined Benfica from Napoli for £15m last summer and is seen as a capable back-up to Spurs striker Harry Kane.
The 25-year-old scored 24 goals last season and was linked with a host of Europe's biggest clubs - including Juventus and Inter Milan.
He has made two appearances this campaign, in the Champions League defeat by PAOK and the 5-1 win over Famalicao earlier in September.
Tottenham head coach Jose Mourinho said on Wednesday he was optimistic of signing a striker before the transfer deadline closes on October 5.
"I am optimistic, but more than that the feeling that I like is that we are trying everything to do it," he said.
"You succeed or you don't succeed. It's like a football match: you win or you don't win but you give everything and try everything. The transfer market is the same.
"I like the feeling that my club is trying to do everything for us and for the team, that's the most important thing for me.
"If we succeed then great - I believe so - but if we don't then that's football."
Celtic have made an approach for Tottenham left-back Ryan Sessegnon - but it is believed the finances of any potential deal have proved problematic.
The 20-year-old was highly rated as a teenager at Fulham but has struggled to break into the Tottenham side since making the move from Craven Cottage for £25m last summer.
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Sessegnon managed only 12 appearances in all competitions last term and has since been pushed further down the pecking order following the arrival of Sergio Reguilon from Real Madrid.
A number of Premier League clubs are also monitoring the England U21 international's situation.
Summer transfer window - key dates and times
The summer transfer window closes at 11pm on Monday October 5 with a feast of activity lined up on Transfer Deadline Day on Sky Sports News and across our Sky Sports platforms.
A domestic-only window for deals between the Premier League and EFL then runs from October 5 and closes on Friday October 16 at 5pm. Follow all the news and analysis on SSN and across Sky Sports' digital platforms, including with our dedicated Transfer Centre blog.