Kevin Nisbet is to undergo a medical at Millwall after Hibernian accepted an offer of around £2m for the Scotland forward.
The Championship club had previously offered just over £1m for the 25-year-old.
Nisbet, with 10 international caps and one goal, has scored seven times in seven Hibs matches this season.
Meanwhile, Ryan Porteous still finalising a deal with Watford and was not at Hibs training on Friday.
Aberdeen visit Easter Road in Saturday's Scottish Premiership match.
The terms of Nisbet's proposed move to Millwall would be life changing for the player, who recently returned from surgery on a knee injury.
He joined the Scottish Premiership club from Dunfermline Athletic for a fee of £250,000 in July 2020, having scored 23 goals in 32 appearances for the Fife club.
The Glaswegian has since played 88 times for Hibs, scoring 34 times, leading to interest from the club sitting eighth in England's second tier.
Millwall are looking to strengthen their front line after selling Isaac Olaofe to Stockport County and terminating the contract of fellow striker Benik Afobe this month.
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Source: bbc.com