Rangers boss Mark Warburton expects more from 25-goal striker Martyn Waghorn

Rangers boss Mark Warburton has backed Martyn Waghorn to get better and better after the striker became the first man in Britain to hit 25 goals this season.

The former Sunderland, Leicester and Wigan hitman hit a hat-trick in Gers' 5-1 win over Cowdenbeath as the Light Blues booked their place in the last 16 of the William Hill Scottish Cup.

His treble took the 25-year-old past Peterhead's Rory McAllister as he became the UK's top scorer in all competitions this term.

However, manager Warburton reckons the Ibrox faithful have yet to see the best of their ace marksman.

He said: The more often he plays the greater his belief in his ability and he'll get better and better. He's on 25 goals in early January and he will get stronger and stronger.

Martyn's target was to play football and, as basic as it may sound, to play week in and out. He is a victim of his own success - at 19 he got his £3million move to Leicester and spent time on the bench in the Premier League but he needed to play.

He's doing that now, developing nicely and there's a lot more to come from Martyn Waghorn.

He did very well today. He's dealing with the expectation here. He came here as a striker to a club like Rangers and the crowd expect, quite rightly, that he delivers - and he's doing that.

He needs that to build his own self-belief to recognise how far he can go in the game. I've known him since the age of 18 and have no doubts about his ability and still think he'll get even stronger from here.''

Gers grabbed the lead after 19 minutes when Lee Wallace was picked out by Kenny Miller before slotting through Cowdenbeath keeper Jamie Sneddon's legs.

Barry McKay cut in from the right to sweep home a stunning second on 33 minutes but there was a setback for the hosts at Ibrox when Dean Brett clipped an exquisite free-kick past Wes Foderingham off the underside of the bar.

But Rangers moved clear again when Waghorn bullied his way into shooting territory before firing over Sneddon.

He then wrapped up his second Rangers hat-trick since moving north in the summer with two penalties after team-mate James Tavernier was twice tripped in the box.

Former Rangers favourite Brian Laudrup will conduct Monday's fifth round draw at Hampden but Warburton insists he is not bothered who the Dane picks out.

We have no preference about who we play next,'' said the Englishman.It was all about being in the next round, delivering a decent performance, and whoever draws Rangers in the next round will know they face a good game.''

Harry Forrester was given his Gers debut off the bench but it was a quiet introduction for the former Doncaster man.

Warburton, though, was again reluctant to confirm whether he was closing in on a £500,000 move for Toumani Diagouraga from his old employers at Brentford.

He said: I'm never going to talk about another club's players - when we conclude our business we can talk about it but right now we have a number of targets because the nature of this game is you have to have options one, two, three and four.

There are a number of players we're looking at and work being done and hopefully we can bring them here.

If not, the squad is top of the league and in the next round of the cup. The squad is strong and we have shown our quality.''