Former Celtic manager Martin O'Neill has insisted that Brendan Rodgers can follow up a double Treble with a European final.

Today marks the 15th anniversary of Celtic's extra-time defeat to Jose Mourinho's Porto in the UEFA Cup final but O'Neill has maintained that the Parkhead side have it within them to repeat that feat.

And the Irishman also believes that the arrival of Steven Gerrard at Rangers can offer Celtic a greater level of competition next term - something that will require Rodgers' side to raise the bar again.

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"I think getting to a European final can be done again," said O'Neill. "I don't think it's impossible.

"Brendan is dominating Scottish football just now and Celtic have been very strong.

"The next step now is to try to achieve success in Europe.

"Hopefully those days are not gone and it would be nice, imagine me saying this, if Rangers could get stronger.

"That seems as if it might be on the cards and a good, strong Rangers is good for the league.

"And actually, it will benefit Celtic to get stronger in Europe.

"Why? Well, Celtic don't rest on their laurels in Scotland but if the competition gets stronger, they will rise to it.

"If Rangers are in a position to delve into the transfer market and get some decent players, it will be a reminder to Celtic.

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"They are dominating the league and are very strong. In Brendan's time, they have not been casual at all.

"They have won six competitions but I think he would welcome it too.

"Personally, I think Steven Gerrard is a really good appointment,

"There is always a viewpoint in terms of inexperience but he is bringing Gary McAllister along, who has lots of experience.

"The combination should be good and I think he will be really good for Rangers.

"Steven was a brilliant player and that doesn't always materialise into being a brilliant manager.

"But he has all the attributes and he wants to have a go. And why not?"

Rodgers made history with Celtic this weekend by leading the club to an unprecedented back to back Treble, something that O'Neill lauded.

The Irishman celebrated a clean sweep in his first season at Celtic in 2000-01 and appreciates the consistency required.

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"It's extremely difficult to do what Celtic have done," he said. "Even the great Jock Stein has difficulty with it.

"Of course, the 1967 side eclipses everything really. That is something to look to all the time for any Celtic manager.

"But it's a great achievement. To do it once is very good. To do it twice on the trot, is excellent.

"They have deserved it too - and played some really decent football."

O'Neill admitted it was strange to walk into the away dressing room yesterday afternoon as he brought his Irish side over to play in Scott Brown's testimonial.

"I went right instead of left into the dressing-rooms," he joked.

"But it was nice. Young Brown has done really well as a player and a leader.

"He has grown into the role in the latter part of his time and it was well deserved."