John Hartson believes that Jonny Hayes is capable of making his mark at Celtic after formalising a £1.3m deal from Aberdeen.

The Republic of Ireland internationalist is expected to conclude his deal by completing a medical this weekend and Hartson believes that Hayes can fill the void left by Patrick Roberts.

Roberts had been wanted by Celtic on a permanent deal but that looks to have fallen through with reports suggesting the England under-internationalist wishes to look elsewhere.

The winger has reportedly been told that he will have this pre-season to impress Pep Guardiola at Manchester City, a chance he is eager to take.

"With Jonny, he is very similar to Pat Roberts whom they have just lost," said Hartson "He can be a player, he has got a goal in him and his performances at Aberdeen have been terrific over the last few seasons. He deserves an opportunity to go and play with the biggest and best team in Scotland. Brendan has obviously noticed that Jonny Hayes is a player whom a lot of clubs down south would like.

"He is a good character with a great attitude and ability. He will have to work to get into the Celtic team like Pat Roberts did at first but when he got in he was effective and Jonny will bring competition for places. He is a quality player and that is the type of player that you need because Celtic need quality. You won’t see Celtic sign an average player or players just to bring in bodies for the sake of numbers. If you are going to sign someone at Celtic, Brendan’s way of thinking is that they have got to be ready to go into his first-team."

And Hartson has also isnisted that Rangers are in danger this season of bringing in too many players as the Ibrox side look to rebuild.

“If you look to Rangers, Mark Warburton brought in 13 last season and how many can you say were a success?" said Hartson. "It is ok bringing in numbers but surely you would rather have three of real quality rather than 10 or 12 to make up the squad.

“It is ok bringing in several players for a million.

"It is hard to pick up players for £1m or £500k and think that they are going to make a difference. You go back to Martin O’Neill’s days – he bought myself for £6m, Chris Sutton for £6m, Neil Lennon for £6m and Alan Thompson and we got to a UEFA Cup final. I know the money is not there now but big clubs want big players to make an impact and make an impact in Europe. You would sooner bring in two or three of real quality. If I was the manager of Rangers I would be asking for £10m and I would bring in 3 players – one at £4m and two at £3m. You might find a diamond like Henrik Larsson for £650k or Brian Laudrup who was a genius for £2.5m but in general big clubs want quality players and Jonny Hayes fits that category."