The SPL leaders ran out comfortable 4-0 winners at East End Park to book their place in tomorrow's quarter-finals draw at Hampden.

Third Division East Fife had sent Queen of the South and St Mirren crashing out of the competition in earlier rounds but there was to be no shock result on the cards this time.

Nacho Novo opened the scoring before Boyd grabbed his 50th goal in 58 starts for Rangers. Carlos Cuellar put the tie beyond the plucky Fifers before Boyd, not satisfied with the half-century, netted again from the penalty spot.

"It's terrific going," said Smith. "He has worked hard this season in terms of his fitness and has done really well for us. I think he is improving as a player.

"The one thing that he has that no-one wants to take away from him is that he sees himself as a goalscorer first and foremost. In the period of time since I came back to Rangers, he has worked extremely hard for the team as well. Without prompting from anyone here he has worked hard on his fitness levels.

"I have absolutely no complaints. I know exactly what he can do. 50 goals in two-and-a-half years in Rangers teams that maybe haven't been that superior to the opposition is testament to him."

Boyd has often been criticised for not working hard enough and contributing little else to matches other than his goals but Smith insists the prolific hitman has nothing to prove as far as he is concerned.

"He has never let it affect him," said the Gers boss. "Kris Boyd doesn't need to show me anything other than what he has shown since he has been here."

Speaking of tonight's tie, Smith added: "These games are always very awkward and you find that the other team is very well motivated.

"East Fife put a lot into the game and we were happy when we got a couple of goals for a level of comfort. At 1-0, East Fife hit the bar and could have been back into the game so we were happy to get this tricky cup tie out of the way."

East Fife branded Rangers' penalty "very, very soft" afterwards but boss Dave Baikie had no real complaints about their flirtation with the League Cup coming to an end.

He said: "For us, it is the end of the run but it has been a good wee run for a Third Division team like East Fife. We beat St Mirren and tonight's game was the reward for us. Now we concentrate on the games in the league."