A Kris Boyd hat-trick allowed Rangers to crank up the pressure on Hearts in the race for second place in the Bank of Scotland Premier League by slashing the gap between the two clubs to just three points.

Hours after Hearts booked their place in the Tennent's Scottish Cup final with a win over Hibernian, Rangers recorded their first victory over Dundee United at Tannadice in almost three years.

That unwanted record finally came to an end thanks to a goal from Dado Prso and Boyd's treble, even though Collin Samuel grabbed a consolation strike for the Terrors.

Hearts had boasted a 16-point lead over Rangers back in December but, with Champions League football up for grabs for the runners-ups, the pressure was now on heading into the final straight.

Only a win over a Celtic team who are just one victory from securing the championship will allow them to restore their six-point cushion on Wednesday night.

Meanwhile, Rangers' celebrations were tempered by the knowledge that the win at Tannadice would probably be Barry Ferguson's final game of the season, after the Ibrox skipper admitted he would soon go under the knife for ankle reconstruction surgery.

It was Ferguson who set up the first chance of the game when he played a short free-kick to Thomas Buffel only for the Belgian international to send his chip an inch wide, before squandering another great chance from a poor Derek Stillie clearance.

The woodwork then proved to be Dundee United's saviour when Prso saw his header come crashing off the post a few yards from goal.

But the reprieve proved to be temporary for United when Prso broke the deadlock with half an hour gone, twisting and turning past David McCracken before dispatching a speculative 25-yard drive into the top corner of the net.

Less than a minute later, Rangers had doubled their advantage following a superb example of free-flowing, creative football.

Again, it was McCracken who was left standing as Prso sought out Peter Lovenkrands, who in turn released Ferguson into the box, with Boyd waiting to collect the ball in front of goal.

All that was required from the striker was to rifle past a helpless Stillie to notch up his 28th goal of the season.

The second half began in controversial circumstances when Julien Rodriguez appeared to bundle over Samuel from behind in the box but the penalty pleas were ignored by referee John Underhill.

Then, to make matters worse for Dundee United, Rangers all but killed the game off when they grabbed their third goal of the day, after 54 minutes.

Prso's initial shot was blocked by McCracken but he regained possession to drive across the face of goal to the feet of Boyd to stab over the line.

Ferguson - who has played most of the season with his ankle problem - was withdrawn with just over 20 minutes remaining and replaced by Gavin Rae.

But Dundee United fired out a warning that the game may not be over when Samuel took advantage of a mix-up between Alan Hutton and Ronald Waterreus to pull a goal back with 68 minutes gone.

Boyd should have found the net when he collected a Buffel ball at the near post only to nod onto the woodwork.

But he made amends by completing his hat-trick after 83 minutes to secure a convincing victory for Rangers.

Buffel was the provider again, sending a corner-kick into the packed box, and it was Boyd who bulleted through a sea of bodies and into the back of the net.

Teams

Dundee Utd Stillie, Mair, Mulgrew, McCracken, Kenneth,McInnes (Duff 72), Kerr, Robson (Robertson 88), Miller,Fernandez (Cameron 89), Samuel.

Subs Not Used: Samson, Archibald, Gardiner, Goodwillie.

Goals: Samuel 68.

Rangers Waterreus, Hutton, Smith, Rodriguez, Kyrgiakos,Ferguson (Gavin Rae 66), Hemdani, Buffel, Lovenkrands,Kris Boyd (Novo 88), Prso.

Subs Not Used: Klos, Ricksen, Andrews, Murray, N'Guessan.

Goals: Prso 30, Kris Boyd 31, 54, 83.

Att: 11,213

Ref: J Underhill (Scotland).