Motherwell's Lionel Ainsworth came off the bench to hit a brilliant 30-yard equaliser against Dundee United in an exciting second-half at Tannadice.
Henri Anier's clinical finish gave the visitors a deserved half-time lead.
But a resurgent United scored twice in three minutes as Nadir Ciftci levelled and Robertson scored his first United goal from distance.
Keith Lasley's free-kick hit the post before Ainsworth's beauty ensured 'Well went four Premiership games unbeaten.
For a long period it looked like it would be four wins in a row that Stuart McCall's men would be celebrating - something they have not managed since 2007.
Andrew Robertson's first Dundee United goal had put them in front after 57 minutes
But the Tangerines got their act together after a terrible opening 45-minute showing and move up to sixth in the league.
They were only denied their first home win against Motherwell since 2011 by a piece of long-distance brilliance by the on-loan Rotherham winger Ainsworth which found the top right corner.
Incredibly, the 25-year-old is the only player other than Estonian international Anier or John Sutton to have scored for the North Lanarkshire side this season, who remain fourth in the Premiership.
Michael Higdon and Henrik Ojamaa's excellent contribution to Motherwell's second-place finish in the league last year is becoming a distant memory now that Sutton and Anier have struck up such a productive partnership of seven goals between them.
Anier's neat chest control and well-struck half-volley into Radoslaw Cierzniak's bottom-left corner left the big Polish goalkeeper with no chance on the half-hour.
It lit up what had previously been a disjointed match and only came about because of some fantastic left-wing-play by Motherwell's Zaine Francis-Angol.
The Antigua and Barbuda international retained his place in the team at the expense of James McFadden after some impressive recent displays.
He shrugged off the attentions of Keith Watson and John Rankin to burst to the byline and cut-back for Anier to apply the lethal finish.
McCall would later regret that earlier assaults on the United goalmouth, through Stephen McManus's diving header and Anier's lash from the edge of the box, had yielded nothing.
The hosts initially showed very little of the attacking threat they seemed to have in abundance at Ross County last weekend, but going behind did give Dundee United a jolt.
Turkish forward Ciftci, again starting in place of the benched David Goodwillie, benefitted from some slack Motherwell defending to fire a low left-foot shot past goalkeeper Lee Hollis, who perhaps could have done better in dealing with it.
More alarming was the manner in which the visiting midfielders stood off and watched Robertson run unchallenged from his own half before the 19-year-old drove the ball past a helpless Hollis from 20 yards.
It was a strike that looked to have given United their second victory on the trot and was only marginally less impressive than Ainsworth's.
The Englishman's equaliser, with 15 minutes remaining, followed Lasley's near-perfect free-kick from 25 yards which had thumped Cierzniak's right-hand upright with him beaten.
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