Celtic are within touching distance of retaining their Bank of Scotland Premier League title after a 1-0 home win over Motherwell.
A 52nd-minute goal by substitute Derek Riordan, who had replaced the injured Maciej Zurawski just before the interval, gave the Parkhead side their first win in four SPL games.
If Rangers lose at St Mirren on Sunday, Celtic will be champions. Otherwise they can wrap the title up against Kilmarnock at Rugby Park in their next SPL game in a fortnight's time.
However, it was another unconvincing display by the home side and they had Riordan, the former Hibernian striker - who has hardly featured this season - to thank for their narrow win.
Zurawski, whose last SPL goal had been in December against Dunfermline, had not started since January 14 in a 2-1 win over Hearts.
Thus, there was some pressure on the Poland striker to justify his selection alongside Jan Vennegoor of Hesselink. But his game was to end in disappointment after he was injured and substituted later in the half.
In the fifth minute, the Dutchman's perfect knock-down from an Aiden McGeady cross found Zurawski who skewed his left-footed drive from 12 yards wide of the target, although there were claims that Motherwell keeper Graeme Smith had got a touch on the ball.
Moments later the Polish international fired wide again, this time from a more acute angle on the right-hand side of the penalty area.
In the 29th minute, Paul Hartley's cross from the right was met by Vennegoor of Hesselink at the near post but the Hoops' striker could only prod the ball wide under pressure from young defender Mark Reynolds.
Moments later, McGeady fended off the attentions of Kevin McBride to drive over the bar from distance, the effort smacking of frustration.
In the 33rd minute, Motherwell skipper Stephen Craigan was booked for a foul on Zurawski which led to the Pole limping off to be replaced by Derek Riordan.
The appearance of the former Hibernian striker lifted the crowd momentarily and seconds later McGeady hit the side netting with an angled drive.
The fuss soon died down and there was little to enthuse the fans before the sound of the half-time whistle.
Hoops defender Lee Naylor picked up a needless booking in the 49th minute for dissent, which was in keeping with the general tetchiness of the match.
However, in the 52nd minute it was Riordan, whose contribution to Celtic's cause this season had hitherto been bit-part, who changed the atmosphere inside the ground when he opened the scoring.
McGeady's searching cross to the far post was headed back across goal by Vennegoor of Hesselink and the former Hibs striker bundled the ball over the line from close range.
It was Riordan's first goal since the start of February when he notched a double against Livingston in the Tennent's Scottish Cup.
But in the 62nd minute, Gary Caldwell had to react quickly to stop Darren Smith getting his shot in on goal from close range after the Fir Park youngster, looking suspiciously offside, had latched on to a mis-hit Kerr shot.
A wonderful curling effort from McGeady which whizzed past the post drew a roar of appreciation from the Celtic fans.
In the 70th minute, Vadocz foolishly fouled Shunsuke Nakamura at the edge of the penalty area but as a hum of expectancy enveloped Celtic Park, the Japanese international fired the free-kick inches wide.
Craig Beattie, who came on for Vennegoor of Hesselink with eight minutes remaining, failed to capitalise on a couple of decent chances and was left in no doubt about the home fans' frustration.
Boruc had to tip over a Danny Murphy header as Motherwell pressed late on and when the game ended, Celtic once again could look back on a patchy performance.
But with the title all but secure, few at Parkhead will worry.
