The striker, on loan from Wolves, was the match-winner in a pulsating cup tie, opening the scoring on 15 minutes and with the match poised at 2-2 he added two more to win it.
"Leigh is a special player, it is not just the goals, his movement is different class but I think there were good performances all round," Fenlon said.
Fenlon's thoughts though have already turned to next week's Edinburgh derby with Hearts.
"It is a good feeling to be in another semi-final but we are just thinking of Hearts to be honest, that's the next game and I am going to make sure we are prepared for that.
"But I was delighted with the performance today."
Griffiths has now scored 22 goals this season and he says he is desperate to go all the way in the competition and banish the memory of last season's "humiliating" 5-1 defeat in the final to Hearts.
"It is not just me who is the Hibs fan, Paul Hanlon is as well and we know what it means to the Hibs fans to win the cup," he said.
"We have the chance to rectify that now. If we get through the semi-final then hopefully we can go one step further.
"The gaffer spoke to us after the game (against Killie) on Wednesday to tell us how important this game was going to be and to get back to Hampden.
"Last year we said, 'is it going to be this year and what better way to do it than against Hearts' and we got absolutely humiliated.
"We embarrassed ourselves and most of all the club last season and we just have to rectify that.
"It was probably the biggest derby there will probably ever be and it was a shambles really.
"Fair play to Hearts they won it, they played better than us on the day. But we are not going to talk about the final just yet, we have important league games coming up starting against Hearts next week."