Shankland's only appearance at the Parkhead ground came during Covid lockdown for Dundee United. They suffered a 3-0 defeat in December 2020 in the eerie closed-doors atmosphere.
A boisterous Celtic support shouldn't overly faze him. As Zurich ultras baited, booed and whistled behind their goal on Thursday in Switzerland, Shankland was the epitome of composure holding the ball after Adrian Guerrero fouled Nathaniel Atkinson inside the penalty area.
He calmly placed it on the spot and drove it unreservedly low into the net, silencing the locals as Hearts played out a 2-1 loss in their Europa League play-off first leg. "I think the linesman gave the penalty eventually.
The ref said 'no' at first but the linesman has obviously seen something," explained the forward. "I was just keen to grab the ball and it took a wee while.