Celtic's title drive stalled at St Johnstone as Keith O'Halloran's diving header halted the Parkhead outfit's pursuit of Scottish Premier League leaders Rangers.

The defeat is Celtic's third against Saints this term and is likely to prove the most costly with an opportunity to draw to within a point of Rangers spurned at McDiarmid Park.

Celtic dominated the opening 45 minutes without finding a goal and at the break head coach Jozef Venglos made an ill-fated tactical switch replacing defender Tosh McKinlay with forward Simon Donnelly.

O'Halloran's strike duly followed and Celtic's rhythm was suddenly gone, and with this first loss of 1999 goes perhaps their ambition of retaining the Championship next month.

With Rangers clearly feeling the pressure at the summit, Celtic sensed an unlikely recovery from being some 13 points adrift at one stage, but now the initiative clearly returns to Ibrox.

Celtic were last defeated at Hearts on December 6, but Saints have proved something of a jinx for them and whatever the outcome of next week's Old Firm match the title may now prove beyond them.

Alan Stubbs' comeback only made it as far as the bench despite Johan Mjallby failing a late fitness test, while Morten Wieghorst earned a first start of the season with Regi Blinker sidelined.

St Johnstone without Alan Kernaghan in central defence opted to flood the midfield with Nathan Lowndes' suspension meaning Miguel Simao led the line alone.

Celtic spurned a clear opening after six minutes when Wieghorst's deep cross picked out an unmarked Jackie McNamara at the far post only for the Scotland international to head tamely into the ground.

Mark Viduka overhit badly an attempted cross from the left on 14 minutes, but McNamara recovered the ball well and advanced rapidly to the byeline on the opposite flank.

His pull-back found Craig Burley who managed a fierce shot on the turn only to see his effort beaten away firmly by Alan Main in the St Johnstone goal.

Paul Kane then rescued Saints by clearing a looped Wieghorst header off the line, while from the rebound Burley saw his strike blocked.

St Johnstone had started in encouraging fashion, but were now on the backfoot as Celtic sustained their momentum and started to look increasingly dangerous.

Henrik Larsson collected the ball from Tosh McKinlay before cutting inside and unleashing an angled drive which again called for Main to be alert.

His counterpart Stewart Kerr's main concern ahead of the break was a wayward Enrico Annoni backpass, which said much about the balance of the contest.

Viduka held up a McNamara ball into his feet brilliantly on the half-hour mark before feeding the Scotland international whose well-struck shot needing tipping over smartly by Main.

Home skipper Jim Weir was brave to deny Vidar Riseth after 36 minutes as the versatile Norwegian aimed to profit from a clever flicked header by Larsson.

McNamara was finding promising positions without producing the necessary finish and was again wasteful after 40 minutes after again being set up well by the hard-working Viduka.

A Larsson free-kick on the brink of half-time was curled narrowly wide of the mark, but there were signs of Celtic frustration as the deadlock persisted to the break.

Reasoning Saints were offering little in attack, Celtic made a positive change at the interval introducing Donnelly for defender McKinlay - only for the switch to backfire.

A Viduka cross from the right found Larsson a minute after the restart but he headed straight at Main, while Sheffield Wednesday-bound Donnelly dragged a shot wide.

It was against the run of play that Saints moved ahead, Simao's cross from the left met by a diving header by O'Halloran to stun the visitors, whose response to adversity was slugglish.

Suddenly St Johnstone sensed room upfield with McKinlay gone and might have doubled their advantage after 62 minutes when Nick Dasovic blazed well wide from distance.

A Riseth error then let in Simao, but his first touch was poor and Kerr was able to claim, that lapse the signal for Stubbs' introduction at Wieghorst's expense.

Celtic had muted claims for a penalty rejected when Lambert looked to have been felled by Gary Bollan in the area, but the visitors were now struggling to rediscover their creative spark.

Stubbs soon became an attacking threat twice going close with headers, the second effort prompting another fine save from the busy Main.

Celtic's final chance of few in the closing stages, was a Larsson free-kick hit well over the bar leaving Rangers the prospect of moving seven points clear if they beat Aberdeen at Ibrox tomorrow.

Teams:

St Johnstone: Main, Bollan, Griffin, Dods, Weir, Dasovic, Kane, O'Neil, O'Halloran (McQuillan 75), Simao (Preston 78), McAnespie (Grant 90).

Subs Not Used: McCluskey, Robertson.

Booked: Dasovic, Simao, Weir.

Goals: O'Halloran 55.

Celtic: Kerr, Boyd, Annoni, McKinlay (Donnelly 46), Riseth, Lambert, Wieghorst (Stubbs 68), McNamara, Burley (Burchill 83), Larsson, Viduka.

Subs Not Used: Brattbakk, Corr.

Booked: Annoni, McNamara, Wieghorst, Burley.

Att: 10,379

Ref: K Clark (Paisley).