Manager Stuart McCall felt Celtic goalkeeper Fraser Forster stopped Motherwell staging a late comeback.
Forster, called up to the England squad on Thursday, denied John Sutton with five minutes left as Celtic won 2-0.
"He's certainly pulling off world class saves - the one he pulled off today was unbelievable," McCall told BBC Radio Scotland.
"One goal with five minutes to go and who knows? You then put pressure on and the crowd get edgy."
McCall has never won at Celtic Park as a manager and his side stay third in the Scottish Premiership.
Anthony Stokes blasted in the host's opener from a tight angle after 'Well goalkeeper Lee Hollis failed to clear.
Soon after the interval, Kris Commons outstripped the Motherwell defence to lob Hollis.
"In fairness to Anthony Stokes, it's a terrific goal," McCall said.
"It takes an incredible bounce away from Lee Hollis. From the angle Stokes was at - I said to our centre-halves 'why didn't you get back on the line?' but you don't expect a shot from there - it's a great finish."
It was Motherwell's first defeat in seven matches and the upcoming international break will give the likes of James McFadden, who missed this game due to a stiff back, time to recover.
"Once we grew into the game I was fairly happy, but both goals are poor from our point of view," added McCall.
"We gave them a little bit too much respect."