A deadline-day signing from FC Zurich that went under the radar with all the focus surrounding Marouane Fellaini's arrival from Everton.
The teen talent impressed against the Reds in the FIFA Blue Stars tournament in his home city and is most at home either at right-back or on the right wing.
An Under-19 international with Switzerland, Janko also qualifies for Gambia from his parentage.
A powerful performer with plenty of presence, he required international clearance before making his United debut - which was at Under-19 level.
"We saw him a couple of times out there and he played right-back, right-wing and also in a right-sided midfield role," revealed Reserves coach Warren Joyce to Inside United. "He did well in all three positions.
"He came over on trial and made the most of his opportunity. He's certainly a powerful boy. There are a lot of things that he has got to improve on but he is strong, quick and can go past people. He's got some raw materials that we can work with."
Janko represented his country against England's James Wilson and Ben Pearson in mid-October and has started to make his mark in the UEFA Youth League