Gould was guilty of a gross error as he watched Urs Fischer's cross from the left touchline sail over his head. Gould was also at fault in an incident which saw Celtic reduced to 10 men, when the captain, Tom Boyd, had to use his hands to keep out a net-bound shot.
The Celtic captain was automatically sent off, but Zurich could not capitalise, because Cesar Sant'Anna struck his penalty low to Gould's right and the keeper kept the ball out.
With the cushion that Harald Brattbakk's 23rd-minute goal provided now gone, Celtic face an unhappy inquisition in Zurich's Hardturm Stadium in a fortnight.
Despite the incessant rain, more than 50,000 poured into Parkhead. Maybe, they were drawn by the fact that FC Zurich were one of Celtic's victims during the successful 1967 European Cup campaign. Certainly, there has been little about the present side in which fans of the champions can take comfort.
Zurich striker Shaun Bartlett had the opportunity to add to Parkhead's misery after just 20 seconds when he pounced on Tosh McKinlay's mis-hit pass. Bartlett was left with just goalkeeper Jonathan Gould to beat, but so surprised was he at his good fortune that he stubbed an ugly finish wide.
Brattbakk could teach anyone a thing or two about missing the target, and the profligate Norwegian ate away at what remains of his tattered reputation with a dreadful miss five minutes later.
Phil O'Donnell created the opening with a fine surge down the left flank which took him past full-back Daniel Tarone, and he squared a perfect ball across goal to pick out Brattbakk. The Celtic striker, with the goal at his mercy, struck his shot straight at goalkeeper Marco Pascolo.
Yet the peculiar nature of Brattbakk dictates that he will always produce when you least expect it. And to Celtic's delight, that was exactly what happened after 23 minutes.
Jackie McNamara's persistence on the right paid off and he delivered a second cross after his first had been blocked. It took a deflection off Francisco Lima Gouvinho to loop perfectly over the central defenders to Brattbakk, who smacked a right-foot volley past Marco Pascolo from six yards.
McNamara denied Bartlett in the 30th minute when he got back to clear the South African World Cup striker's shot off the line with Gould beaten.
Bartlett was to have a central role in the dramatic seconds just before half-time, when Boyd performed his diving save with his hands. Jozef Venglos was forced to reshuffle, with Craig Burley removed from his midfield role to sit deep.
Celtic (4-4-2): Gould; McNamara, Boyd (capt), Mahe, McKinlay; Donnelly, Burley, Lambert, O'Donnell; Brattbakk, Larsson.
FC Zurich (4-4-2): Pascolo; Tarone, Hodel, Fischer (capt), Di Jorio; Sant'Anna, Del Signore, Lima Gouvinho, Nixon; Bartlett, Chassot.
Referee: Vasily Melnichuk (Russia).Reuse content