Celtic missed the chance to knock Rangers off the top of the Scottish Premier League after 10-man Dundee United held them to a 1-1 draw at Parkhead on Saturday. Australian Scott McDonald rescued a point for the Hoops as he headed in an equaliser after David Goodwillie had fired United into an early lead. Tony Mowbray's men had been handed a pre-match boost with the news that their Old Firm rivals, who stay top on goal difference, had been held to a goalless draw by Motherwell. But the Hoops failed to capitalise against a Dundee United side who had Scott Robertson sent off three minutes before the end and remain unbeaten this season. United started sharply and Goodwillie had a shot blocked in the opening minute before finding the back of the net five minutes later. Margaro Gomis supplied the cross from the left and, as the ball broke off Glenn Loovens, the Dundee United striker turned and his powerful rising shot rifled past Artur Boruc into the top corner from six yards out. United could only hold on to their advantage for 11 minutes as McDonald headed Celtic level from a controversial free-kick. The United bench were incensed when a free-kick was awarded against Scott Robertson for handball when Nial McGinn smashed a cross off his arm from point- blank range. Daniel Fox's perfect delivery wide on the right from the resulting set-piece found the Australian lurking at the back post and he nodded past Nicky Weaver. McDonald looked odds on to get his second in the 23rd minute when Nial McGinn, in his first start for Celtic, crossed from the right but Weaver somehow got a fingertip to the ball to divert it away from the Socceroos star. United started the second-half brightly and the Hoops had Fox to thank for keeping them level when he stole the ball away from the feet of Goodwillie just as he was about to pull the trigger. Minutes later Swanson rode the challenge of Marc Crosas and sent a curling shot round Boruc which went inches wide of the goal. Mowbray brought on Georgios Samaras in the 58th minute and the Greek striker thought he had given Celtic the lead a minute later but his header was chalked off for off-side. The Hoops gained inspiration from this and Irishman McGinn came close with a powerful low drive after the ball broke to him on the right following Maloney's surging run into the box. United were reduced to 10 men with three minutes remaining after Robertson, who had already been booked for a foul on Maloney, received his second yellow for a tripping Samaras. Celtic were screaming for a penalty in injury time when Andreas Hinkel's cross appeared to hit the arm of Darren Dods but referee Steve Conroy waved away their protests as United secured a point. In the early kick-off, Allan McGregor saved a Jim O'Brien penalty four minutes from time as 10-man Rangers secured a goalless draw against Motherwell. Gers defender Madjid Bougherra was sent off after receiving two yellow cards - the first for the challenge which led to the penalty before the Algerian was booked for dissent as he protested the decision. Hearts game against Kilmarnock at Tynecastle was called-off after the Glasgow to Edinburgh motorway was closed due to a lorry fire with the Killie team bus caught in a seven mile tailback. St Mirren and St Johnstone drew 1-1. 