Johnny Kenny marked his full Celtic debut with his first goal for the club as the much-changed champions won 5-1 at Aberdeen.
The Sligo striker netted 25 goals while on loan with Shamrock Rovers last year and he headed home Celtic's fourth early in the second half at Pittodrie.
Maik Nawrocki also headed his first goal for Celtic with Yang Hyun-jun, Luke McCowan and Adam Idah also on target.
Kevin Nisbet had equalised for the Dons but their hopes of finishing third in the William Hill Premiership were well and truly extinguished.
And the nature of the defeat, coming off the back of Sunday’s 4-0 defeat by Rangers, will dent their fans’ confidence ahead of the Scottish Gas Scottish Cup final against Celtic.
Both sides rang the changes from their weekend games, Brendan Rodgers swapping out eight players while the Dons showed six alterations.
Yang and Paulo Bernardo both had a couple of early chances while Pape Gueye and Topi Keskinen came close at the other end.
James Forrest missed a glorious chance to net in his 16th consecutive season for Celtic when Kenny’s blocked shot fell into his path. Despite switching feet well, he somehow turned past the post from close range.
The deadlock was soon broken in the 31st minute. McCowan’s corner found Nawrocki, mismatched against Keskinen at the back post, and the Pole headed home.
Aberdeen levelled almost immediately after a five-minute pause for a medical emergency in the crowd. Gueye lofted the ball into the six-yard box for Nisbet to head past Sinisalo.
Celtic could have gone back in front when Bernardo’s corner was headed goalward by Auston Trusty, but deflected behind off Alexander Jensen.
Jensen’s luck ran out deep in first-half stoppage time as a Forrest cross was palmed by Dimitar Mitov off the Dane, falling kindly for Yang to turn home from close range.
McCowan put the game beyond doubt within three minutes of the restart when he finished calmly after good work from Forrest.
Mitov again denied Forrest before McCowan found space wide on the left to clip a cross for Kenny to head powerfully home from six yards.
The Dons' night got worse as on-loan Tottenham defender Alfie Dorrington saw red with 12 minutes remaining. Having been cautioned for an early challenge on Yang, he was handed a second booking by Steven McLean for bringing down sub Idah.
The Celts were toying with Aberdeen now and Idah was denied by a firm Mitov hand as the visitors piled pressure on the home goal.
Idah turned home from close range in stoppage time after Nicky Devlin’s clearance from a Forrest shot came off Mitov and fell kindly for the hitman.
St Johnstone were relegated after Ross County scored a penalty in the sixth minute of stoppage time to rescue a 1-1 draw away to Dundee.
County's Ronan Hale smashed home from 12 yards following a handball decision against Dundee’s Antonio Portales to condemn Simo Valakari’s side to the drop after they lost 2-1 away at Hearts.
A first-half own goal by Barry Douglas and an Alan Forrest strike for Hearts at Tynecastle left St Johnstone needing the result at Dens Park to go their way, knowing that should they lose only defeat for County would leave them still fighting on the final day.
Graham Carey gave them hope of putting their fate back into their own hands but by then winger Scott Tiffoney’s goal for Dundee had looked like providing them with a crucial lifeline.
That was until Ryan Astley headed the ball against the arm of his teammate Portales at the death and Hale stepped up to end St Johnstone’s 16-year stay in the top flight.
Cyriel Dessers hit a brace as Rangers came from behind to beat Dundee United 3-1 at Ibrox, with Nicolas Raskin also scoring for Barry Ferguson’s team after Sam Cleall-Harding had earlier given United a first-half lead.
Hibernian are guaranteed a third-place finish after they drew 2-2 away to St Mirren.
The home side hit back to earn a point after being two goals down after 10 minutes, while Motherwell scored three times in the final 13 minutes to beat 10-man Kilmarnock 3-0 at Fir Park.
