Celtic showed no signs of a European hangover with an impressive 6-2 thrashing of Dundee United in their Clydesdale Bank Premier League encounter at Parkhead.
The Hoops had been humbled 3-0 at home to Juventus in the first leg of their Champions League last-16 tie on Tuesday night, but responded well to losing a 10th-minute goal to Tannadice midfielder Stuart Armstrong to surge ahead through defender Efe Ambrose, Kris Commons and Joe Ledley.
At 2-1, Fraser Forster made a great save from a Jon Daly penalty, and Commons grabbed his second from the spot 10 minutes into the second half before Anthony Stokes notched a double to complete the rout, with Johnny Russell scoring late on for the Taysiders. The win took Celtic 18 points clear of Motherwell at the top of the table.
However, the visitors had not appeared cowed in the early stages, despite the fact that they had have not won away to Celtic since Boxing Day 1992. Mackay-Steven robbed Charlie Mulgrew near the touchline and sped towards goal before playing in Armstrong, who did not break stride before drilling his shot low past Fraser Forster and into the far corner.
However, they barely had time to celebrate as a minute later Ambrose powered in a header from a Commons corner, and Neil Lennon's men hardly looked back. Left-back Emilio Izaguirre crossed for Celtic's second goal in the 21st minute as Commons hammered it past the helpless Radoslaw Cierzniak.
Forster then emerged a hero when United were controversially awarded a spot-kick in the 25th minute. Adam Matthews appeared to tackle Mackay-Steven cleanly with most in the stadium anticipating a corner but referee Bobby Madden enraged the home support when he pointed to the spot before booking Matthews and the protesting Forster.
Forster parried Daly's penalty and with that setback, United appeared to crumble. Celtic piled forward and in the 37th minute, Ledley's deflected shot from 16 yards ended up behind the hapless Cierzniak.
United started the second half positively but Celtic raced up the park and Gary Hooper screwed a drive from 16 yards just wide of the far post. However, Commons made it 4-1 from the spot after Douglas was adjudged to have fouled Stokes.
There were no shortage of goalmouth incidents as United capitulated. Stokes, clearly desperate to get on the scoresheet, drew a good save from Cierzniak with his long-range drive before Mulgrew clipped Common's pass from a free-kick over the bar.
Stokes eventually got his goal in the 71st minute when he hammered home from the edge of the box, before doubling his tally from six yards after Cierzniak had parried a header from James Forrest, on for Victor Wanyama. In the final seconds, Russell grabbed a goal for United after forging his way into the Celtic box but it provided scant consolation.