So much for the start of a green-and-white procession towards the title. Having just cruised beyond their nearest challengers, Celtic promptly ran into a roadblock. It was built by a deeply determined St Johnstone side seemingly inspired by a return to the scene of the greatest day in the club’s history. Danny Swanson wasn’t on the books when they lifted last season’s Scottish Cup, yet his winning strike here was worthy of its own place in the memory banks of every Saints fan. With that pure, powerful swipe of his right boot, Swanson not only lifted his team into the Premiership top six, but kept Celtic within six points of Aberdeen. A run of ten successive domestic victories – a sequence which had granted Ronny Deila a new level of acclaim from Parkhead supporters – was brought to a shuddering halt. St Johnstone's Danny Swanson marked first Scottish Premiership start with a glorious first-time effort . Bookmakers will hardly be hiking their odds on them ending up with a four successive league crown. That much can still be viewed as a racing certainty. Here, though, was evidence that the odd chicane may still have to be negotiated en route. By the next time Celtic play in the top-flight – at Dens Park on March 18 – they will have come through Scottish Cup last eight and League Cup final meetings against Dundee United. Their Treble ambitions will be much clearer after that double-header, but any repeat of the wayward sluggishness shown last night will place the much-desired clean sweep in peril. To focus only on the failings of the Parkhead side would, however, be a gross injustice to St Johnstone. Not for the first time in his tenure, manager Tommy Wright produced the ideal tactical plan for his charges to follow. Celtic's Leigh Griffiths can't hide his disappointment after the defeat by St Johnstone . They had numerous fine performers and defended doggedly, occasionally desperately, throughout. But it wasn’t only Swanson who brought a touch of class. In David Wotherspoon, who operated just off central striker Steven MacLean, they had the most impressive overall contributor on show. Now two points ahead of Dundee, Wright’s men look well set for a fourth consecutive top-half finish. The Parkhead pitch is far from pristine as spring approaches but that couldn’t entirely account for the sloppiness Celtic showed in the first half. Compared with some of their recent showings, this was turgid stuff at times. As expected, they still dominated both possession and chances, yet Alan Mannus wasn’t exactly in need of a lie down at the interval. Anthony Stokes – making his first appearance since being late back from Dublin prior to the first leg against Inter Milan – offered the first flicker of threat with an angled shot whipped across the face of goal. Perhaps the most fluid move of the opening period then led to Gary Mackay-Steven striking a wicked curler first-time. Mannus stretched high to thwart it before denying Stokes on the follow-up. Celtic manager Ronny Deila sits dejected in the dugout o Wednesday night . Leigh Griffiths was being rationed on opportunities at the apex of Deila’s side. He took matters into his own hands with a low, left-foot thump that zipped fractionally wide from almost 30 yards out. The striker then threatened to hare clear down the left when released by Craig Gordon’s quick throw, only to be halted by a Swanson foul straight from the ‘professional’ drawer. The Saints midfielder earned both a yellow card from referee Calum Murray and a jabbing finger of rebuke from Scott Brown. Nir Bitton had dropped to the bench after showing signs of tiredness against Aberdeen, which meant Stedan Johansen taking a step back to partner Brown in central midfield. It was far from a radical alteration but the pieces weren’t quite clicking into place. Stuart Armstrong looked as likely as any in Celtic colours before the break but his rising drive was beaten away by Mannus. St Johnstone were persistently stretched but kept going about their defending in an organised manner. There were, though, only the most fleeting signs of danger at the opposite end of the field. Danny Swanson (far right) celebrates with his team-mates after scoring against Celtic . Jason Denayer was forced to divert a Michael O’Halloran shot behind, before David Wotherspoon had their clearest opportunity of the half. After Efe Ambrose was hustled off the ball, Wotherspoon cut along the 18-yard line but failed to find the space on either side of Craig Gordon. Deila opted for a switch at half-time, introducing Wakaso Mubark for Adam Matthews. The attack-minded Ghanaian slotted in at left-back, with Ambrose shifted to the opposite flank. The move carried an element of risk, with Wakaso looking unsure defensively, but Celtic fell behind to a 53rd minute strike they could have do nothing about. Swanson watched Wotherspoon’s corner being headed out and stepped forward to connect with a quite brilliant half-volley that arrowed past Gordon from 25 yards. Expect it to feature on all forthcoming goal of the season showreels. Saints should have gone two in front in quick succession when another somehow found its way through to Steven Anderson. It was, though, a case of wrong man in the right place as the centre-back miscued wide from around eight yards. Celtic goalkeeper Craig Gordon attempts to catch the ball in the air under pressure . Deila had watched it all from the edge of his technical area with increasing concern. He played his final hand before the hour mark, withdrawing Mackay-Steven and Stokes for James Forrest and Bitton. That allowed Johansen to step forward into his more regular role and help bring about the inevitable rise in pressure. Mannus made a terrific stop to thwart an Ambrose headed from Johansen’s corner before then grasping a Bitton daisy-cutter at the second attempt. Another Amstrong shot was calmly clutched to his chest. The signal for only two minutes of added time brought loud jeers from the home support. Rightly, they suspected that last night was simply one of those occasions when their team would need a lot longer to find the net.
On-loan Coventry midfielder Danny Swanson scored winner for Saints . St Johnstone up to sixth and Aberdeen given fresh hope in title race . Celtic suffer shock defeat after 10 domestic victories in a row this year .