The title holders will now go into their Europa League tie with Partizan Belgrade next Thursday evening with great confidence although they'll need to improve on what was a far from perfect opening half.

There was a lethargic start from both sides with neither side looking to force the pace although Gary O'Neill escaped down UCD's left flank in the ninth minute but his inviting cross was marginally too high for the in-rushing Billy Dennehy.

UCD offered a sporadic threat of their own as midfielder Paul O'Connor got in behind Enda Stevens in the 11th minute but his cross-shot had too much pace for Dean Marshall who failed to make a decisive connection.

The action returned to the opposite end within two minutes when Gary Twigg was unlucky not to score on two occasions in the space of sixty seconds.

His initial attempt was courtesy of an inswinging Dean Kelly cross which Twigg deflected towards goal only to be denied by the feet of UCD keeper Gerard Bannon from eight yards.

As the Students struggled to clear their lines, Twigg played a delicate one-two with Craig Sives before unleashing a rising drive from the edge of the box which narrowly flew wide of the target.

It seemed that the Hoops would assume dominance from that point but UCD, and O'Connor in particular, reminded them of their capabilities as he struck a powerful shot from 25 yards which beat Ryan Thompson's despairing dive but also the right-hand post by a matter of inches.

Twigg, naturally, was at the hub of most of the Hoops' attacking salvos and he should have scored in the 29th minute when he raced onto O'Neill's delicate through ball but hesitated fatally in front of goal, allowing Michael Leahy to execute a superb last-ditch tackle.

If Leahy excelled on that occasion, he was slightly more fortunate seven minutes before the break when poor communication between Leahy and Barron almost ended up in a calamitous own goal but the latter's header from a Stephen Rice delivery drifted agonisingly wide of the unguarded net.

The second-half resumed with Graham Rusk trying a speculative shot from 25 yards which failed to trouble Thomspon unduly before Rovers siezed the initiative with the introduction of substitute Gary McCabe on the hour the catalyst for their improval in fortunes.

In the 62nd minute, McCabe raced down the right-flank onto to O'Neill's ball and his well-timed cross was flicked beyond Barron from six yards by the inrushing Twigg for his 13th league goal of the season.

As the heavens opened with a torrential downpour, the floodgates opened on the pitch with Dan Murray availing of confusion in the UCD reargaurd to hammed high to the net after the Students had failed to deal adequately with a Dennehy corner in the 65th minute.

Dennehy added a third within two minutes, powering home from the edge of the box following sloppy defensive play from the by-now ragged Students and it wasn't long before the fourth arrived as O'Neill gained tangible reward for an impressive display with a tidy finish for the fourth goal in the 69th minute.

Twigg turned provider for substitute Ciaran Kilduff to score against his old club in the 84th minute and the students' misery was complete as Thomas Boyle headed powerfully past his own keeper from eight yards in injury time, boosting the Hoops' goal difference in the process but not sufficiently to overtake league leaders Derry City.

SHAMROCK ROVERS: Thompson; Sullivan, Sives, Murray, Stevens; Kelly (McCabe, 59), McCormack (Kilduff, 74), Rice, Dennehy (Moore, 70); O'Neill, Twigg.

UCD: Barron; Harding, Leahy, O'Connor, Nangle; Belhout, Creevy (Ledwith, 68), Corry (Doyle, 82), O'Connor, Marshall (Boyle, 68); Rusk.

Referee: Paul Tuite (Dublin)