But he hopes his ex-player doesn’t net against the Republic of Ireland when they face the Scots in the vital Euro 2016 qualifier in Dublin on June 13.
The Irishman was the Celtic star’s manager at Easter Road two seasons ago when the striker netted 28 goals and picked up the SPFA Player of the Year award.
Fenlon said: “I’m delighted Gordon has picked Leigh for Scotland. There is no doubt he is good enough for international football.
“I just hope he doesn’t score against us next month!
“When I got to Hibs in 2011, I was told Leigh was a serious talent, but that there was a big question mark over him.
“That was all about what he got up to away from the field because on it he was fantastic.
“He needed to mature and keep himself away from certain situations. He has done that.
“Signing for Celtic has been the making of him.”
Fenlon, now managing Shamrock Rovers, added: “Leigh is a genuine good lad. His attitude and application were superb. I had no problem with him at the training ground and at games.
“It was during his own time and what he got up to which was a worry.
“There were times I had to drag him off the training pitch. He was so determined to improve every aspect of his game. He just loves playing football and was one of the best trainers at the club.
“My guess is that Scott Brown has been a positive influence on him. Scott’s own attitude is exemplary and I believe he has taken Leigh under his wing.
“I’m not surprised by how well Leigh is doing. He’s always had it in him. He is one of the best finishers I have ever seen.
“He scores with both feet and is good in the air. His link-up play has improved immeasurably.
“I saw him linked with Leeds, but he is not going to leave Celtic to go to there.
“He is at the right club for his progress – and he is going to get much better.
“I had to look after him for a bit when he was getting into a spot of bother. However, I can’t speak highly enough of him as a guy.
“He was a pleasure to work with and I still keep in touch with him.”