Celtic are 45 minutes away from the Scottish Cup final after taking in a 1-0 lead at half time against Inverness Caledonian Thistle at Hampden Park.
Virgil van Dijk's free kick has given the Scottish Premiership leaders the advantage at the break as Ronny Deila's men remain on course for the treble.
Inverness were calling for a penalty when the ball hit Emilio Izaguirre inside the area, but the official waved away the appeals before Stefan Johansen's goal-bound effort was well blocked.
Nir Bitton nearly broke the deadlock on 13 minutes when he pounced on a loose ball to thunder a shot against the upright from 25 yards out.
Leigh Griffiths brought a save out of Ryan Esson with a powerful strike from range as Deila's side pushed for the opening goal.
James Forrest skipped away from Gary Warren before he was brought down, and the subsequent booking now rules the Inverness defender out of the final, should they get there.
From the resulting free kick, Van Dijk curled home his ninth goal of the campaign to give Celtic the lead.
Edward Ofere spurned Inverness's best chance of the half when he reacted sluggishly to a rebound inside the area, firing wide from six yards out.
Celtic were left furious when they were denied a penalty after Inverness defender Josh Meekings handled the ball off the line in stoppage time, and a chorus of boos from disgruntled Bhoys' fans greeted the half-time whistle.
