Goals from Odsonne Edouard and Mohamed Elyounoussi saw Celtic ease to a 2-0 Europa League Group E home win over Romanian side CFR Cluj.
Neil Lennon's side took a deserved 20th-minute lead on Thursday night when Callum McGregor released Boli Bolingoli, whose cross was met by the head of Edouard.
As the rain lashed down in the second period, James Forrest found Elyounoussi who fired into the bottom corner via a deflection to double the advantage.
With Lazio coming from behind at home to beat Rennes 2-1, Celtic's win sees them move top of the group with four points ahead of a mouthwatering double-header with the Italian side.
Celtic: Forster (7), Elhamed (7), Jullien (7), Ajer (6), Bolingoli (7) Brown (7), McGregor (7), Forrest (7), Christie (8), Elyounoussi (7), Edouard (7)
Subs: Hayes (6), Ntcham (6)
CFR Cluj: Arlauskis (7), Susic (5), Boli (6), Burca (5), Camora (5); Bordeianu (6), Luis Aurelio (5), Djokovic (5), Deac (6), Rondon (6), Omrani (5)
Subs: Paun (5), Culio (5), Golofca (5)
Man of the match: Ryan Christie (Celtic)
How Celtic gained Romanian revenge
Seven weeks ago, Celtic were shocked in Glasgow by the very same Cluj side as a 4-3 Champions League defeat saw them lose 5-4 on aggregate and miss out on Europe's elite club competition for a second season running.
Ahead of their Europa League meeting, Lennon declared his side "were in a better place" this time out and urged his side to start the game on the front foot to cast aside any lingering fears of history repeating itself.
After a succession of corners that saw Christopher Jullien cause havoc in the Cluj box, Edouard deservedly broke the deadlock to send the home fans into raptures.
Neil Lennon named an unchanged side from Celtic’s last Europa League performance away to Rennes.
However, there were two changes from the draw with Hibs at the weekend with Elyounoussi replacing Ntcham and Elhamed coming in for Bauer.
Cluj were always a threat on the counter in the opening period but Fraser Forster was rarely troubled after the break.
Celtic completely controlled the second half and as well as Elyounoussi's goal, they should have been further out of sight as Forrest, Christie and Edouard had further opportunities.
In the end, the revenge was sweet, but more importantly, the three points even sweeter as Celtic finished the night in pole position at the top of the group.
'We should have won by more'
Celtic boss Neil Lennon said: "We were outstanding, the only disappointment was that we didn't win the game by more.
"We looked really strong and thoroughly deserved the win. From one to 11, I thought we were very good against a very good side.
"We have to be really satisfied by the performance and topping the group. I think there is more to come."
Man of the match: Ryan Christie
Celtic striker Edouard may get the plaudits for scoring Celtic's opening goal and producing a polished performance but Ryan Christie excelled in the number 10 role.
The tireless Christie covered almost every blade of grass in the attacking third of the pitch and linked up superbly with Edouard and the lively Forrest, particularly in the second half.
Furthermore, Christie was also on hand to make defensive contributions too when Romanian club Cluj ventured forward.
Analysis: Reporters view
Sky Sports' Luke Shanley...
It's been 51 days since their Champions League exit at the qualifying stage by the Romanian outfit, which gave this game an interesting sub-plot.
Cluj themselves dropped into the Europa League and by a quirk of fate were reunited with Celtic.
From the off the home team were out to prove a point and even though the main focus and motivation was on three points, you could tell the players wanted to put on a show.
Celtic dominated almost from start to finish, the player were up for it and so were the crowd. It is hard to believe Celtic lost 4-3 to Dan Petrescu's men on August 13th.
In truth it could have been more for Neil Lennon's team, who now top the group and Lennon was rightfully delighted post-match after watching a dominate display by his team.
He had to take criticism after his team selection in the previous meeting but this is the sort of occasion he relishes and with a double header against Lazio to come, he will be happy with how his team have started their Europa League campaign.
Celtic might still have some regret about the one that got away against Cluj in the summer but they proved a point and gained three.
- Since losing 3-4 to Cluj at Celtic Park in a Champions League qualifying match in August, Celtic have remained unbeaten in their following 11 games in all competitions (W9 D2).
- Celtic's 2-0 win over Cluj was their biggest European group stage win at Celtic Park since beating Rennes 3-1 in the Europa League in November 2011.
- Celtic have four points after their first two Europa League group stage matches; their joint-best start to a campaign in the competition since 2014-15 (also four points).
- Cluj have lost away to a British side for the first time since December 2008 (2-1 loss against Chelsea), this after winning in each of their previous two trips.
- Celtic forward Odsonne Edouard has scored in five of his last six appearances at Celtic Park in all competitions, netting six goals.
Celtic travel to Livingston on Sunday (kick-off 12pm) for a Scottish Premiership game live on Sky Sports Football.
Their next Europa League match sees them host Italian side Lazio on Thursday, October 24 (kick-off 8pm).