Hoops midfielder Callum McGregor made it 2-0 in the second-half with a deflected drive before Jags midfielder
Stuart Bannigan reduced the deficit in the final seconds with a contentious penalty.

Lennon said: "Leigh has been looking sharp and played well and scored a striker's goal. He is a great player, a great scorer.

"He has had fitness issues and other issues.

"He had a good (training) week in Dubai and looked sharp in training this week so I know what I have got with him and there is more to come from him, obviously.

"We don't score may goals like that and he does."

Lennon left Maryhill believing referee Alan Muir got two penalty decisions wrong in the game, first by ignoring Celtic pleas with a spot-kick when right-back Jeremie Frimpong went to ground after clashing with James Penrice in the first-half.

And then in added time, when he awarded a penalty to the Championship side after Frimpong put pressure on Thistle substitute Dario Zanatta to miss an open goal.

The Northern Irishman said: "It is a definite penalty (for Celtic). It is a push in the back. He has gone past him and the guy pushed him in the back.

"Jeremie is at full pace, he hasn't dived, he has gone over so I don't know how that can't be a penalty.

"The second one, I think he got his body across Zanatta.

"There was an inference that his heels were clipped but you can clearly see he has got his body across and his recovery and desire to get back – he didn't deserve that."

Thistle boss Ian McCall was pragmatic in defeat.

He said: "Ultimately it's a cup tie and we're out, so it's not great.

"The first 20 minutes, we couldn't handle Tom Rogic and Odsonne Edouard changing positions like they did.

"But we got to grips with that and I don't think they had any real chances after that, even though they had a lot of the ball.

"The deflection has killed us – Callum's claiming the goal but it was going safely into the keeper's arms.

"And at 1-0 you're always going to get a chance.

"The penalty, I'm not sure it was, a few of the boys expressed their doubts, but ultimately that goal didn't matter anyway.

"We probably should have scored just before half-time through Kenny Miller and gone in at half-time 1-1, but listen, the endeavour and the shape of the team and the performances of some individuals were really good."