It will take a long time for the events of last May to be erased from the minds of Martin O'Neill's players. Two prizes in four days slipped through Celtic's fingers; they have responded with a stranglehold.
Nothing will compensate for losing the Uefa Cup final in extra-time to Porto, or the cruel way O'Neill's team summoned up one last effort after the heat of Seville on the final day of the Scottish Premier League season only for Rangers to snatch the title from them by the narrowest margin of just one goal.
Yet, if revenge is a dish best served cold, then the east end of Glasgow seven months later was the perfect place for payback time. "Happy New Year", chanted the gleeful Celtic supporters as their rivals slipped out of Parkhead after O'Neill's team had opened up an 11-point gap in the championship race.
A third title in four seasons under O'Neill is now there for the taking. The Celtic manager watched his side enter the record books with an 18th successive League victory, eclipsing Jock Stein's side of 1968-69, before brushing aside comparisons with the manager he calls "immortal". However, such is Celtic's strength that they could soon put the League to bed and focus on another European final, 12 months after their last. It did not seem like a consolation three weeks ago when a late penalty in Lyon eliminated them from the Champions' League, but the Uefa Cup is now a prize that will drive Celtic on.
FK Teplice, of the Czech Republic, now await in the third round next month for a club that appears to have exorcised all their ghosts of last May. The Celtic supporters even found time to mock Nuno Capucho, whose move from Porto to Ibrox last summer seemed like the ultimate insult.
Instead, the joke has been on Rangers. Capucho has been a much-criticised figure and even though he had scored last week at Dundee, Alex McLeish had no faith in the Portuguese player's stomach for this kind of battle, leaving him out of a second successive Old Firm derby.
When Capucho finally made his bow in the 74th minute, it was to ironic cheers of "bring on Capucho" from the green and white hordes. Indeed, the slim and lethargic figure sums up his team at the moment - and the difference between it and a robust Celtic side who want to write a fresh chapter in history.
"People described us as losers because we didn't win anything last season," Jackie McNamara, the captain, said. "While we were disappointed not getting a trophy, the memories we had getting to the Uefa Cup final is something I would not change. Losing the title by a goal was also tough, but there has been no difference in our approach.
"Records come and go. It's not fair to compare us to Jock Stein's team. They were fantastic and played a different style of football. All I know is that this is the strongest squad I have seen at Celtic. It was hard for me simply to get in the team last season and while Henrik [Larsson] appears to be going, the rest of us are desperate to stay."
That is bad news for Rangers. They may have suspected that their rivals held the upper hand before goals from Stilian Petrov, Stanislav Varga and Alan Thompson inflicted a punishing defeat, but the manner of Celtic's victory will trouble those in power at Ibrox.
O'Neill is creating an epoch at Parkhead that could cast a long shadow across the city. The place has become a fortress, which is why Rangers always looked unlikely to get the victory they required to trim the deficit to five points. It is now 68 games since Celtic have lost at home: that was against Ajax in the Champions' League, while the only other loss was against Dundee in May 2001 after the manager's first title had been wrapped up.
"Celtic can only lose it now," McLeish conceded. "We have to hope that they drop points but we also know we must win every game now if we are to catch them. Their aerial presence caused us problems and we were second best in that department." That was underlined when Bobo Baldé set up Varga's thumping header in the 59th minute to double Celtic's lead after Petrov's diving header in the 19th minute had set them on their way. Thompson sealed the success with a 30 yard free-kick for the watching Tord Grip. "It was a world class finish," drooled O'Neill. "But the players know they must drive on from here."
Goals: Petrov (19) 1-0; Varga (59) 2-0; Thompson (84) 3-0.
Celtic (4-4-2): Douglas; Agathe, Baldé, Varga, McNamara; Petrov, Lennon, Sutton, Thompson; Larsson, Hartson (Miller, 82). Substiututes not used: Hedman (gk), Maloney, Wallace, Crainey.
Rangers (4-5-1): Klos; Ricksen, Berg, Moore, Ball; Burke, Malcolm (Capucho, 74), Arteta, Rae (Mols, 34), Arveladze; Lovenkrands. Substitutes not used: McGregor (gk), Vanoli, Ross.
Bookings: Rangers: Ball, Arteta, Moore, Lovenkrands.
Referee: S Dougal.
Attendance: 59,087.Reuse content