Celtic manager Neil Lennon says he should shoulder the blame for his side's failure to beat Dundee United following a hard-fought 1-1 draw at Parkhead on Saturday. The Hoops needed a last-gasp goal from Charlie Mulgrew to earn a point that preserves their unbeaten start to the Scottish Premiership. Dundee United looked to be heading for their first win at Celtic Park since December 1992 thanks to a first half strike from Stuart Armstrong. However, Mulgrew popped up two minutes into stoppage time to head Emilio Izaguirre's cross past Radoslaw Cierzniak to keep his side five points clear of Inverness Caledonian Thistle after 11 games.