"We shall not be moved!" they sang, evidently very moved at seeing Rudi Skacel's poacher's goal so quickly cancel out Craig Beattie's deflected opener. The chant will echo throughout at least another week in the title race, and hopefully - for the sake of Scottish football - much longer.
Because what this result represented - aside from keeping Hearts top, unbeaten, after eight wins and two draws in 10 games - was a third significant statement of intent against the clubs who occupied the top three spots in last season's Scottish Premier League table. Early in the campaign, Hearts walloped their Edinburgh rivals, Hibernian - third last season - 4-0.
Three weeks ago, they beat last season's champions, Rangers, who finished 43 points clear of Hearts, 1-0. And now Celtic, the in-form half of the Old Firm, have been held on their own patch.
The weekend's service at the cathedral that is Parkhead opened with a stirring, scarf-waving "You'll never walk alone" from some 58,000 fans. When Beattie scored, the intensity of the celebrations was something quite different. Old Firm-esque animus. It was place-putting gloating, a noise that said: "And you thought you'd come here and get a result? NAAAHHHH!!" Which meant that when Hearts showed the character and ability to get back and stay back, the Celtic fans were dumbstruck.
Skacel, as usual, was a handful. That he was booked for celebrating his goal was bewildering, because the referee was on hand and did nothing, but then a linesman, who was 40 yards away, urged a yellow. "A ridiculous decision," said Hearts' manager, George Burley, afterwards.
Skacel was aided and abetted by Paul Hartley, who makes his midfield tick, while the defence was again magnificent, even in the absence of Scotland goalkeeper, Craig Gordon, suspended. Steve Banks deputised admirably. Hearts could use options up front but that might be addressed this week when the German international striker, Fredi Bobic, 33, arrives on trial as a free agent, meaning he could sign immediately if wanted.
Celtic purred at times, especially when Shunsuke Nakamura or Shaun Maloney ran with the ball, but stuttered in front of goal at others. A point apiece was a fair result in front of Britain's biggest football attendance of the weekend for one of its most entertaining games in what is without doubt now a much more competitive élite league than the one-horse race down south.
Goals: Beattie (13) 1-0; Skacel (16) 1-1.
Celtic (4-1-3-2): Boruc; Telfer, Baldé, McManus, Camara; Lennon (Hartson, 70); Nakamura (Agathe, 84), Petrov, Thompson (Maloney, 63); Sutton, Beattie. Substitutes not used: Marshall (gk), Virgo, McGeady, Wallace.
Heart of Midlothian (4-1-3-2): Banks; Neilson, Pressley, Webster, Fyssas; Brellier; Camazzola, Hartley, Skacel; Pospisil (Elliot, 78), Jankauskas. Substitutes not used: MacDonald (gk), McAllister, Simmons, Mikoliunas, Wallace, Tall.
Referee: D McDonald.
Booked: Celtic Sutton, Thompson; Hearts Skacel, Pressley, Brellier.
Man of the match: Skacel.