The 24-year-old has always played as a full-back for Newcastle, but his switch to winger is certainly working at Millwall.
His spell at The Den continues until January and he looks set to be an important part of the Lions’ push for the play-offs.
Harris said: "He is a great lad.
"He has added some balance to our left-hand-side, has the right attitude and plenty of ability.
"He took his two goals very well.
"I think he was a bit agrieved when he missed a chance at Blackpool to make it 2-0 from a similar position but this time he converted well.
"He works very hard at his game. Often he is the last one on the training pitch, practising free-kicks and things like that.
"It is important we score goals from all over the park."