Aberdeen boss Derek McInnes claims Celtic's struggle to keep pace with Rangers cannot be pinned solely on Neil Lennon.

Lennon resigned this week after defeat by Ross County left the Scottish Premiership champions 18 points adrift of their Old Firm rivals at the top of the table.

McInnes takes his team to Celtic Park on Saturday and is disappointed not to be facing Lennon, who won the first five domestic trophies on offer during his second spell in charge.

"I class Neil as a friend and a colleague and we have been well-versed to playing against each other both as player and manager," he said. "He is someone I have a high regard for.

"It's really disappointing to see any manager lose his job but I know how important the Celtic job is and was to Neil.

"What has to be said is he is a very successful Celtic manager. Sometimes in the here and now, particularly in Neil's case this season, he has been a bit of a punchbag for others and he has had to take a lot on the chin, and a lot of criticism has come his way.

"I think when you see the difference points-wise Celtic to Rangers, it's more than a manager at fault there if people are blaming anybody.

"Time will be kind to Neil. It might not be that now because a lot of people got themselves into a real state this season, the 10-in-a-row thing comes into that, but Neil has been a very successful manager in both spells.

"In time, even people who have been heavily criticising Neil will see the merits in what he has achieved.

"Neil's a good manager and he will go on and show someone else he is a good manager."

Lennon had come under serious criticism from fans and McInnes himself recently faced pressure which prompted his chairman to give him the board's public backing.

A 1-0 win over Kilmarnock last Saturday ended a run of six goalless performances and kept the Dons five points behind Hibernian in the race for third.

McInnes knows he will have to continue living with criticism and feels it is getting more prevalent in the modern game.

"We can't do anything about that," he said. "When you sign up to be a manager you have to expect a level of criticism that comes your way when your team don't win.

"You get the flip side of that when you're winning games, the praise at times can be a bit overboard. But I have always tried to keep a balance on that.

"As managers that's becoming a bit more difficult. I get asked a lot more on outside pressures than I do on the game now.

"I speak to managers from a different era, I speak to Walter (Smith) quite a bit, and I do think they look on with astonishment on what we have to contend with now.

"But it is outside pressure, that's what you have to keep reminding yourself. The job is still to work closely with your players and get your club as competitive as possible."

Aberdeen's recent struggles in front of goal came amid a complete turnover of their attacking options and injury to Ryan Hedges, and they suffered another major blow when recent loan signing Fraser Hornby tore a thigh last weekend.

But McInnes is hopeful the injury is not as bad as it appears.

"We will get it re-imaged again in a couple of weeks because the length of tear in the scan would suggest he is going to be out for a long time, but when you listen to the player and how he is presenting over the last couple of days, he is actually feeling better than the scan suggests," he said.

"Scans have been wrong in the past and we just have to hope he can get back a bit quicker."