Rod Stewart celebrated Celtic 's crunch victory over Rangers with a sing-song with fans after the match.
The Hoops-daft rockstar watched Neil Lennon's men win a tempestuous affair at Parkhead after beating their rivals 2-1, a result that all-but secured an eighth consecutive title.
The 74-year-old joined singer Liam McGrandles in a post-match duet of Irish ballad Grace, which has rang out in the stands in recent years.
Stewart released a version of the song last year, which tells the story of Grace Gifford, who married her doomed fiance Joseph Plunkett just hours before he was executed in Kilmainham Gaol as one of the leaders or the 1916 Easter Rising.
Fans sang along with the pair who were clearly revelling in the occasion, with McGrandles describing Stewart as "buzzing".
Celtic-daft Rod Stewart parties with Hoops fans after Old Firm win
One wag referenced one of Stewart's hits as he referenced the empty glasses in front of the pair, tweeting: "I am steamboats, I am steamboats."
Another said it was great to see the pop star "having a bevy with his pals".
Last week, McGrandles was joined by Scott Brown for a version of terrace favourite Discoland at a charity event in Donegal.
Earlier, Stewart had arrived ahead of the game sporting green and white hooped socks and a pair of slippers that read "Cel" and "Tic" on either foot.
Rod Stewart leaves Celtic boss Neil Lennon cracking up as he gatecrashes interview
He was then pictured revelling in victory at full-time and later gatecrashed Lennon's chat with Celtic TV.
Lennon had just watched his side move 13 points clear at the Premiership during a game littered with incidents.
Odsonne Edouard opened the scoring before Alfredo Morelos was sent off for the visitors.
Ryan Kent levelled for 10-man Rangers but James Forrest had the final as he tucked home the winner with 86 minutes on the clock.
