It was an opening day to forget for Gary Locke as his side were second best to the visitors all afternoon.
Greg Stewart put the away side in front after 34 minutes when he cut inside from the right and curled a great effort into the top corner.
It got even better for Paul Hartley’s side in first-half stoppage time when Rory Loy got on the end of a Kevin Holt cross to double his side’s lead before the interval.
Loy was on target again just two minutes into the second half as he headed home from a Gary Harkins cross before Stewart rounded off the scoring when he thrashed the ball into the net from 12 yards.
Hamilton and Partick Thistle shared the points with a 0-0 draw at New Douglas Park, despite the away side having to play with 10 men for the majority of the match after Frederic Frans was sent off for two bookable offences after just 25 minutes.
New Thistle goalkeeper Tomas Cerny was in inspired form in the second half which included a miraculous stop from Ali Crawford.
Greg Docherty also hit the post for Accies following some intricate build-up play, but the home side were to endure a frustrating afternoon as Alan Archibald’s team returned to Glasgow with a point.
After securing their Premiership status via an emphatic play-off win last season, Motherwell picked up an encouraging opening-day victory in the Highlands as they beat Scottish Cup holders Inverness Caledonian Thistle 1-0.
New Well signing Wes Fletcher bagged a debut goal after four minutes, reacting quickest to Owain Fon Williams’ parried save from Stephen Pearson to poke the ball into the net.
Williams ensured his side did not fall further behind after 27 minutes, however, when he saved Scott McDonald’s penalty.
Watch Dundee United v Aberdeen live on Sky Sports 1 HD from 3pm on Sunday.