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McGregor marked his return to action with a superb all-round display, capped with a goal that sent Ange Postecoglou's side nine points clear at the top of the table.
Celtic created 33 chances to Aberdeen's two across the 90 minutes, but were frustrated by some wayward shooting and an inspired performance from Aberdeen goalkeeper Kelle Roos.
Unsurprisingly, Postecoglou felt his visitors deserved all three points. "I thought we were in total control of the game and dominated them from start to finish," the Australian said.
"We were really disciplined in our approach and didn’t get frustrated because it would have been easy to get frustrated, and I thought we got the rewards we deserved.
Postecoglou reserved special praise for his captain McGregor, who blasted home the 200th competitive goal scored by Celtic under the form Australia coach's charge.
"The skipper was outstanding today," Postecoglou said. "We've done awfully well to stay consistent without him but you know that he’s just a fantastic footballer and such a big influence."
McGregor himself was also delighted to be back after being forced to sit on the sidelines since October.
"It was brilliant," he said. "It’s always a difficult game up here [at Aberdeen] and it was the same again today, although I thought we dominated large parts of the game but at times it probably just didn’t drop for us or our quality wasn’t quite there in the final third."
McGregor paid back the praise given to him by Postecoglou with some words of his own for his Aussie boss.
"Having the character and resilience to go right to the end and get the winner was brilliant," he said.
"The manager’s been massive on that since he’s come in, in terms of mentality and going right to the last whistle, and you’ve seen how many times we’ve done it now over 18 months. It’s not a coincidence, it happens by design. It’s about having a real strong mindset and believing in the structure that he gives us to play in, and just be brave. And normally, fortune favours the brave, in football as well."