Celtic stumbled to a 1-1 draw after the Scottish Premier League champions were stung by a late goal from Dundee United new boy Francisco Sandaza. The Spaniard, formerly of Valencia, popped up in the 78th minute to steer an angled shot past Artur Boruc in only his second game for the Tannadice side.
It was the visiting goalkeeper who was the busiest in the first ten minutes, as Boruc was called to deal with a floating Willio Flood free-kick and tip a dangerous David Robertson header over the bar. Celtic's first foray came in the 17th minute, when a Shunsuke Nakamura corner ruffled a few United feathers before they cleared with the imposing figure of Jan Vennegoor of Hesselink bearing down.
Scott Brown and Andreas Hinkel combined in the 21st minute, but the Germany international's final ball went straight into the hands of Polish keeper Lukasz Zaluska. Vennegoor of Hesselink had a good opportunity after 33 minutes from a whipped cross of ex-United player Mark Wilson, while Nakamura continued to provide teasing crosses.
An Aiden McGeady shot from 20 yards stung the gloves of Zaluska on the 40-minute mark, in what was the last decent action of the first period. Dundee United have not beaten Celtic since 1999, and at the interval they must have fancied their chances after matching Celtic in every part of the field.
However, the Bhoys made the breakthrough on 50 minutes. Nakamura neatly cut inside to lay the ball off for Paul Hartley, whose crisp shot took a deflection on its way into the back of the net.
Celtic went in search of a goal that would have effectively ended their hosts' hopes. An interchange from McGeady and McDonald provided a golden opportunity for Vennegoor of Hesselink, who, clear on the Tangerines' goal, failed to convert.
Roy O'Donovan spurned another excellent chance in the 71st minute, as the Glasgow side lived dangerously and United looked the more hungry. And Craig Levein's side showed they had an appetite for the big upset when Sandaza, who had just came on as a substitute, sneaked into the six-yard box to slot home the equaliser.
Scott McDonald missed a clear-cut chance in the last five minutes, heading wide from close range, and Dundee United held on for a well-deserved draw.
It was a disappointing result for the SPL holders, whose arch-enemies and chief title rivals Rangers beat Hearts 2-0 yesterday. It took the Ibrox team on to six points from two games, behind leaders Hamilton Academical on goals scored.