MARTYN Waghorn scored a hat-trick as Rangers cruised into the last 16 of the William Hill Scottish Cup with a 5-1 thrashing of Cowdenbeath at Ibrox yesterday.

Mark Warburton’s team were 2-0 up after just over half- an-hour after Lee Wallace and Barry McKay netted.

Cowdenbeath pulled one back with a brilliant Dean Brett free-kick just before the break but Waghorn claimed the match ball with three second-half goals – including two from the penalty spot – as Rangers booked their place in tonight’s fifth-round draw.

Former Wigan forward Waghorn has now overtaken Peterhead’s Rory McAllister to become Britain’s top scorer in all competitions this season with 25 goals from 27 games.

Warburton disappointed those in the 20,000-strong Ibrox crowd eager to see new signings Harry Forrester and Maciej Gostomski by naming the pair as substitutes.

The Rangers manager made two changes, with on-loan Arsenal teenager Gedion Zelalem making his first start in just under a month, coming in for Nicky Law in midfield, and Dominic Ball returning from flu to replace Rob Kiernan at the back.

Cowdenbeath knew they would be up against it in their encounter with the Ladbrokes Championship leaders but hoped 14-goal striker Greig Spence might be able to repeat his cup heroics against the Ibrox side with previous clubs.

However, it was clear from the outset that the hosts were never going to be tested. Waghorn and Kenny Miller both went close before the breakthrough arrived after 19 minutes.

On-loan Arsenal midfielder Gedion Zelalem’s ball from wide in to Waghorn’s feet was cushioned to the feet of strike partner Miller. The former Scotland international did well to look up and spot the run of Wallace and played a perfect pass for the left-back to run on to before slotting through Jamie Sneddon’s legs for the opener.

Rangers, on form again after back-to-back wins over Hibernian and Dumbarton, re-established them as the Championship promotion race leaders added a second when McKay sped away from Brett, cut inside right-back Bradley Donaldson and swept a perfect finish across the goalkeeper after 33 minutes.

There was a setback for the home side four minutes before half-time when Dom Ball’s foul on Spence just outside Rangers’ box presented their League One visitors with a free-kick chance. Brett took it in style, clipping a precision set-piece off the underside of Wes Foderingham’s crossbar and into the net.

However, it took just three minutes of second-half action for Warburton’s men to pull away again. American teenager Zelalem flicked a Miller pass into Waghorn’s path and the bullish Englishman held off Fraser Kerr before driving a fierce strike over Sneddon.

After Kerr brought down James Tavernier as the full-back drove into the Cowdenbeath box in the 56th minute Waghorn was able to put memories of his recent penalty miss against Falkirk to rest by stroking home the fourth from the spot.

Forrester was handed his debut soon after but it was a relatively quiet introduction.

Waghorn had time for one more goal, though, as he rounded off his treble with another penalty after 78 minutes after the galloping Tavernier was again brought down inside the penalty area, this time by Chris Kane.