BT SPORT pundit Stephen Craigan has explained why the linesman did not flag for offside for Kyogo Furuhashi's contraversial winning goal against Hearts at Celtic Park on Thursday.

The Japan internationalist swept home an Anthony Ralston cross shortly after the half-hour mark but television replays appeared to show that the striker had drifted into an offide position.

The goal stood as Ange Postecoglou's men ground out a 1-0 victory, leaving Hearts head coach Robbie Neilson furious at the final whistle.

"I felt we didn’t get beaten by Celtic, we got beaten by poor decisions by the referee and linesman," he said.

Glasgow Times:

"We can all laugh and joke about these things. I made a comment after our game at Ibrox and got the book thrown at me, so I can’t say too much about this one.

"But it’s offside. He’s ahead of the ball. The linesman has got to see it. I’ve seen it, everyone would agree. The linesman had a brilliant view."

Craigan, however, believes it is understandable that the linesman didn't flag for offside - because unless the assistant is absolutely certain of their decision, they cannot intervene.

“What I would say on referees assistants is unless they are 100 per cent convinced that they know what happened, they can’t put the flag up or they can’t draw the attention to the referee," Craigan told the Go Radio Football Show.

"I remember speaking to [former referee] Stuart Dougal about it and I said, 'you must know' and he said, ‘listen, we don’t give things unless we’re 100 per cent'.

"So unless they see it, they can’t give it. I just think that the referees assistant's position is a yard ahead of the ball.

"So he has no idea if Kyogo is in line with Tony Ralston or not because he’s had a position to see that.

"If he’s standing directly behind Ralston, he will see it clearly. And if he thinks he’s offside then his flag has to go up.

"That’s why I don’t think he put his flag up.

"I also know some referees have said in the past - I don’t know what happens now - ‘I’m in charge, don’t put your flag up unless I want to draw attention to you. I’ll deal with it. If I want you to help, I’ll come to you'. 

"That’s some referees taking control."