Celtic extracted retribution from Cluj with a commanding 2-0 Europa League win at Parkhead.
The Hoops were knocked out of the Champions League qualifiers on aggregate by the Romanian outfit in August, following a shock 4-3 home defeat, but this time they found Celtic a different proposition.
French striker Odsonne Edouard headed in the opener in the 20th minute as the Scottish champions dominated amid cascading rain.
Attacker Mohamed Elyounoussi added a second on the hour mark with a deflected drive to confirm a well-deserved win
Following the 1-1 draw against Rennes in France on matchday one in Group E, the Scottish champions are on four points and now face a double-header against Italian side Lazio which will go a long way to deciding their future in the competition and after this performance they can certainly be confident of progression.
Neil Lennon had urged Hoops fans to turn up the volume ahead of the game and they were in good voice as the home side, with full-back Hatem Elhamed and Elyounoussi back in the side, started with the purpose and pace also demanded by the Parkhead boss.
Dan Petrescu's side, knocked out of the Champions League play-off by Slavia Prague and who started the section with a 2-1 home win over Lazio, were forced to work hard to keep Celtic at bay.
In the 10th minute Cluj's Lithuanian keeper Giedrius Arlauskis made a great save from Christopher Jullien's powerful header from a Callum McGregor cross and a minute later the French center-back headed over the bar, again from close range.
However, it was another Frenchman who got the breakthrough 10 minutes later when overlapping left-back Boli Bolingoli ran on to McGregor's perfectly-weighted pass down the left and crossed for Edouard to bullet in a header from six yards out.
Cluj could not get a foothold in the game but in the 25th minute, after McGregor was booked by referee Daniel Siebert for fouling Mihai Bordeianu 25 yards from goal, they had the ball in the Hoops net only for the offside flag to correctly go up.
Celtic keeper Fraser Forster parried Ciprian Deac's low left-footed drive and Mario Rondon sent the ball back across goal from the rebound to be turned into the net by defender Kevin Boli but celebrations were cut short.
James Forrest drove forward and fired wide at the start of the second half as Celtic quickly reasserted their dominance.
It was the Hoops winger who set up the second goal, laying the ball back to Elyounoussi whose shot from outside the box deflected past Arlauskis for his first goal since signing on loan from Southampton in the summer.
Cluj were forced to go forward and left gaps which the home side did their best to exploit.
The tireless Ryan Christie almost got on the end of an Elyounoussi cross in the 79th minute and then the Parkhead midfielder drove an effort wide.
The home side did not need any more goals to underline another compelling European performance in the east end of Glasgow.