Charlie Nicholas reckons "old school" Shane Duffy will improve Premiership champions Celtic.
But the former Hoops star is concerned the Republic of Ireland captain might not be an ideal fit for Neil Lennon 's favoured formation.
Celtic secured a season-long loan for the Brighton defender last week and he could make his Hoops debut against Ross County on Saturday,
Nicholas approves of the signing but the the 58-year-old has also shared his concerns over Duffy's suitability of starring for Celtic in Lennon's preferred 3-5-2 set-up.
Speaking to the Express, he said: "Shane Duffy's biggest challenges as a Celtic player will be in the Europa League games because very rarely do the team get challenged domestically, especially at Parkhead.
"The Irishman was at his best as part of a back four at Brighton when he partnered Lewis Dunk.
"When Graham Potter took over and wanted a centre-half to pass the ball out of a three-man defence, Duffy found himself out of the team.
"He is an old-fashioned centre-back. That's what Celtic needed and now they have one.
"He is not the quickest but he will improve Celtic and give them a bit more steel."
Duffy admits he has some way to go after admitting he wasn't quite up to speed during Ireland's UEFA Nations League double header with Bulgaria and Finland.
“It’s been tough, very tough. I haven’t played a lot of football in a year. That’s where I want to be, playing every week. I know it’s not perfect, I’m my biggest critic and I’ve got to improve and keep going.
“I know what I need to do, to get back to my best.
“Them slight seconds for the goal the other night, you’re tired. You try and stay up and go on the run.
“I back myself and I don’t see many players really getting the better of me. I’ve got to deal with big spaces and being on the ball, I’ve got to get better with that.
“It’s easier said than done. I keep going back to it, we’re not at match fitness."
