Ajax winger Viktor Fischer is Teesside bound, according to reports in Holland.
The report claims the two clubs had previously reached an agreement over the 21-year-old's transfer, with Boro to pay an initial €5 million (£3.8 million).
Fischer is now said to be flying to England, having left Denmark's training camp on Tuesday.
The eight-cap international was used sparingly by Frank de Boer in 2015-16, but still managed to score eight goals and create a further three as the Dutch giants narrowly lost out to PSV Eindhoven in the race for the Eredivisie title.
However, with only a year to run on his contract at the Amsterdam ArenA, Fischer looks to be on the move.
Boro, who announced the release of Jonathan Woodgate, Damia Abella and Rhys Williams this morning, are awaiting their first signing after their promotion back to the Premier League at the start of the month.
According to a report in Tuesday's Sun newspaper, Boro are keen on West Ham United winger Michail Antonio, although the capture of Fischer could put paid to their interest in the 26-year-old.