Sky Sports football pundit Neil McCann believes Celtic have put down a significant marker in their pursuit of a fifth consecutive Scottish Premiership title with the weekend defeat of Aberdeen.
Aberdeen were five points clear of Celtic in mid-September after an eight-match winning streak - which included a 2-1 defeat of Ronny Deila's side at Pittodrie - but a miserable return of one point from their last five games has seen them slide to third place.
Strachan urges Deila to focus
Gordon Strachan has advised Ronny Deila to "deal with reality" and ignore media
McCann told Sky Sports Now: "It's not job done for Celtic and although Hearts are six points behind I don't think they are equipped to challenge Celtic, although they have had a remarkable season thus far.
"I really thought Aberdeen were the ones to challenge Celtic but they have let a five-point advantage slip to seven behind. A 12-point turnaround in such a short space of time is quite alarming.
"It's a different mindset when you are leading the league it's a fine margin. Against Celtic on Saturday, Adam Rooney had a fine chance with header and he didn't take it and then Leigh Griffiths scored with a wonderful header; he's on fire at the moment and Scotland manager Gordon Strachan was saying how much he has improved.
"Celtic putting Aberdeen to bed that was a big result without their captain Scott Brown. It was almost putting a marker down to Aberdeen saying 'You still not there yet.' Aberdeen had chances against Celtic and unlike Hearts in the League Cup in midweek, they gave it a go on Saturday. I still think if anyone is to challenge Celtic it will be Aberdeen."
McCann was also impressed with Hibernian over the weekend as they derailed Rangers' hopes of an unbeaten Championship campaign with a 2-1 win at Easter Road.
Rangers had won 11 consecutive league games but the home side prevailed on Sunday and McCann hopes to see both teams in the Premiership next season.
He said: "Possession does not win you games. It's people who want to go and get on the end of things when the chances come up, and show that extra willingness to go and make things happen as Paul Hanlon did for the set piece.
"If Rangers had gone 11 clear it would have been done but now it's down to five and it's still game on. Stubbs before the game was really confident and that must have transmitted to the players. What a great game of football it was and these two clubs have to be back in our top league."