The former England winger was in the home end at Parkhead on Sunday as Martin O'Neill's side stormed to a 3-1 win
David Bentley knows all about derby day.
A Tottenham fan brought through the ranks at Arsenal - who would eventually go on to play for boyhood club Spurs - the North London rivalry is up there with the best of them in England.
But nothing quite compares to the Glasgow derby.
Bentley has ticked some of the world's biggest games off his football bucket list - including the El Clásico between Real Madrid and Barcelona.
However, after savouring his first Old Firm, the ex-England star reckons Celtic vs Rangers tops the lot.
Bentley was in the home end alongside ex-Hoops youngster Paul Slane as the pair filmed a vlog for podcasters Open Goal.
And the 41-year-old was blown away by the deafening noise inside Parkhead as Martin O'Neill's side stormed to a 3-1 comeback win to move within two victories of a sensational title.
He told Sky Sports: "Absolutely amazing. The energy, the atmosphere is one of the best I've been in.
"I was behind the goal with the fans filming. I think it was one of their biggest games in 10 or 15 years potentially.
"It's all on the line, the league this year. What Martin O'Neill has done for the club with his positivity as well...
"The fans sing their heart out before the game, after the game. That's why I've got a croaky voice!
"The atmosphere is probably number one. It's amazing. Better than El Clásico? I think it is. I mean, that was amazing as well.
"The intensity, the two teams - Rangers and Celtic - there's a lot more on the line. Their rivalry runs deep and to witness that and be a part of it, it's incredible.
"The energy within that stadium was frightening; it was a lovely day. They were singing their hearts out and were going for it. The atmosphere was incredible."
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