Giorgos Giakoumakis added a brace and Daizen Maeda also got on the scoresheet with Elie Youan opening his account for Hibs with the visitors’ consolation.
Lee Johnson made two changes to his side, bringing in Lewis Stevenson for Marijan Čabraja and giving Harry McKirdy his first start in place of Youan as the Hibs boss explained he was focused on communicating with a starting XI including ten English speakers.
Too bad no one warned the Hibs four as they were cut off with far too much ease, Sead Haksabanovic’s cross falling for Forrest to tap in at the back post.
Just five minutes later it was two, with Celtic breaking quickly down the left and Alexandro Bernabei’s cross perfectly timed for the rushing Giakoumakis to cushion a shot past David Marshall.
Celtic looked menacing every time they advanced, but their third was a personal disaster for Marshall on his league return to Parkhead. His defense did him a disservice, but when the ball fell on Forrest at the edge of the box, his shot was straight at the keeper. Ninety-nine times out of 100 would be an easy meeting, but the keeper fumbled the line. He may have been blindsided and there are certainly questions to ask the defence, but it’s not one the captain will want to see again.
There were no further goals in the first half and Johnson sounded the changes in the interval, throwing over Čabraja, Youan, Kyle Magennis and Rocky Bushiri for Stevenson, McKirdy, Mykola Kukharevych and Chris Cadden as Hibs changed shape at 3-5. -2.
Initially it worked as Boyle played Youan ten minutes after the break and he beat Joe Hart at his near post to cut the deficit, but it just seemed to irritate Celtic as Forrest restored their three-goal lead following an error by Nohan Kenneh to score. his 100th goal for the Hoops and his hat-trick of the day.
Bushiri sent a header just over a corner and Magennis tested Hart from distance, but Hibs looked shocked and likely to be caught apart with every wave of attack.
Fifteen minutes later, Giakoumakis added his second and Celtic’s fifth, sweeping home from the edge of the box from substitute Liel Abada’s reduction via Bushiri, whose touch carried it away from Marshall.
Demi Mitchell made a return to action for the first time since the opening day of the campaign, replacing Kenneh for the final 12 minutes or so, and he wasn’t too far off to connect with Čabraja’s cross at the over time.
Marshall made a nice late save to deny Abada, but seconds later Daizen Maeda stepped in, clipping in the sixth via the far post.
It was a dark day in Glasgow for Hibs with few positives to come from a one-sided encounter. Barring a spell shortly after half-time when Youan scored and the visitors looked a little more threatening with altered form, Celtic were dominant and in the end Hibs will be grateful to have kept it at six.
