Ben Gibson has signed a new four-year deal with Middlesbrough.
The central defender has made only one appearance for Boro but has gained experience at loan spells with Plymouth and York.
The 19-year-old had been enjoying a loan spell at Tranmere this campaign but has returned to the North-East to receive treatment for a troublesome abductor problem.
Manager Tony Mowbray told the club's official website: "He's done extremely well at Tranmere.
"At some time in the next year or two, Ben Gibson is going to be knocking on the door of the first team.
"He's a very, very mature young guy who's very focused and knows what he wants from his career.
"In terms of talent, composure and ability, it's all there."
The former Republic of Ireland international watched Celtic beat Barcelona and Spartak Moscow at Parkhead to upset the odds and make the knockout stages.
Only Barcelona have beaten Celtic in Glasgow in the Champions League proper with the Hoops racking up 15 wins in 22 matches over the years.
And Coyle feels Celtic should not fear the arrival of any of their possible opponents, who are Paris Saint-Germain, Schalke, Malaga, Juventus, Bayern Munich, Borussia Dortmund and Manchester United.
Coyle, who turned down the chance to be Celtic boss in 2009, said: "I've been to the last four games and I'm as excited as anybody else because I think it's brilliant for Celtic to be in the last 16 and it gives the whole of scottish football a boost.
"Regardless of who their opponents are, then there is no doubt they will be uneasy about facing Glasgow Celtic.
"The home record that Celtic have got in the Champions League is second to none.
"You look through Europe and it's an unbelievable record.
"The first game that Celtic have will be the home game. Regardless of who they play, I think they are going to be in very good shape going into the second leg of that last 16, and who's to say what they can achieve?"
Celtic manager Neil Lennon has pinpointed Dortmund and Manchester United as opponents to avoid.
"Neil will know best who he will want to play," Coyle said. "Regardless of who it is, you don't get to the last 16 without being of outstanding quality, so it's going to be a top team.
"But equally they will know as well that Celtic will be a real test for whoever it is they undertake."
Meanwhile, Coyle remains open to an approach from the Scottish Football Association as he waits for the right opportunity to return to management.
The former Bolton, Burnley and St Johnstone manager has been without a job since being sacked by Wanderers in October.
Coyle has been linked with the vacant Scotland manager's post since Craig Levein was removed from the post last month but the SFA have so far taken their time to assess possible candidates.
Coyle, who was at Hampden today to launch a first-aid training project for coaches at grassroots level, said: "When the right opportunity comes about, then I'll know what it is.
"Equally people that think you're worthy of that consideration will know as well because they will know the ambition I have and how I like to go about it. And when you get that it will be a good match.
"That's exactly where we are. There have been a couple of things that were put to me that I didn't think were quite right for me at this moment in time.
"We are certainly not in any rush in terms of taking something that's not right for me, but when the right opportunity comes around I'll know what it is."
