Rob Maclean on Kieran Tierney, Kenny McLean, Hearts and Raith Rovers
BBC commentator Rob Maclean provides his take on a weekend of Scottish Cup action.
Tierney tackle worth celebrating
There were 34 Scottish Cup goals across the weekend and that total would have been 35 had it not been for my favourite fifth round moment.
There would also have been a replay at Firhill had Kieran Tierney not denied Partick Thistle a stoppage-time equaliser at Celtic Park with an impeccably-timed last-ditch intervention.
Ryan Edwards must have thought he was scoring from only a couple of yards out as Chris Erskine's pinpoint cross dropped in front of him.
But 20-year-old Tierney saw it all unfolding and his speed of thought was matched by the sliding challenge which ensured Celtic beat Thistle 3-2 to reach the quarter finals.
He quite rightly celebrated as if he'd scored.
Hearts contenders for glory
If Celtic's double treble bid falters, Hearts could be a decent bet to end the season with some silverware.
The Craig Levein makeover has made them very difficult to beat. They've lost only one of their last 15 matches and that was at the home of the champions.
Hearts can boast a clean sheet in 10 of their last 12 games. That's enough of the stat attack, but you have to admit it's an amazing recent record.
Their football is getting easier on the eye as well. Levein's first base was always going to be a solid defence. Now, there's more freedom for Hearts to express themselves up front.
They've already beaten two top-flight teams, Hibs and St Johnstone, to reach the Scottish Cup last eight and will quietly fancy themselves to go all the way.
McLean rises to occasion
Getting £300,000 from Norwich City and keeping Kenny McLean for the rest of the season is a smart bit of business by Aberdeen.
The English Championship side weren't willing to wait for the former St Mirren midfielder's contract to expire in the summer and run the risk of him moving elsewhere.
So they signed McLean last month and agreed to leave him at Pittodrie on loan in the meantime.
Maybe settling his immediate future was exactly what he needed, because I don't think I've seen McLean play much better than he did in Sunday's 4-2 Scottish Cup victory over Dundee United.
It was a polished performance and maybe his best days for the Dons are still to come.
Raith Rovers on a roll
Relentless Raith Rovers will take some stopping in their bid to make a quick return to the Championship.
When they lost 3-0 to leaders Ayr at Somerset Park in mid November, the Kirkcaldy team were three points adrift of top spot in League One.
But, following Saturday's 2-1 defeat of Airdrie, coming back from a goal down, they're now eight points in front with 11 games to go.
Second-placed Ayr do have an extra match to play, and could still scrap it out for the title and automatic promotion, but Raith have an impressive momentum about them.
Barry Smith's side have lost only one of their last 13 games and have their sights set on getting back to the league above.