MANCHESTER - MANCHESTER United manager Sir Alex Ferguson vowed to keep faith with his fringe players in the League Cup quarter-finals after Carlos Tevez's penalty sealed a 1-0 fourth round victory over Queens Park Rangers.

Tevez, making a rare first-team start this season, claimed only his second goal of the campaign after converting from the spot following Peter Ramage's foul on 17-year-old substitute Danny Welbeck at Old Trafford.

Ferguson made eight changes to his starting line-up against the Championship outfit and, although youngsters such as Rodrigo Possebon, Darron Gibson and Jonny Evans struggled to make an impression against the west London club, the United boss insists that he will stick with his policy of shuffling his squad - regardless of who United draw in the last eight.

Ferguson said: 'The ones who will need the game will definitely be involved in the next round, no matter who we are drawn against'.

'The attitude of the players was very good against QPR, though, and I am pleased to go through'.

'The patience in their game was good, as was the speed of the football. QPR haven't lost a lot of goals recently, so it was always going to be difficult'.

QPR, sitting comfortably in seventh spot in the Championship, frustrated United for long periods.

Ferguson's team improved slightly after half-time and Rafael Da Silva skipped past two Rangers players and slipped the ball to Park Ji Sung, whose drilled effort from 15 yards beat Radek Cerny but bounced away off the post.

Tevez found some space shortly after when Park blocked Damion Stewart but Cerny managed to tip the Argentinian's effort from 12 yards over the bar.

Just after the hour, United stretched the visitors once again when Tevez found Anderson on the left but the Brazilian's low strike was blocked by Cerny.

The breakthrough arrived in the 76th minute when Nani slipped through for Welbeck and the substitute's run was ended by Ramage's trip six yards out.

And from the resulting penalty, Tevez sent Cerny the wrong way to give United the lead at last.

Ferguson admitted that his team's failure to convert their chances is becoming a regular occurrence.

He said: 'We are used to teams coming here and being hard to break down now. It was just a matter of opening them up and taking the first chance'.

'That was difficult. We created a lot of chances, but at the moment they are just not going in for us. That will come, though'.

'Danny Welbeck is an exceptionally talented young lad, but he has been out for quite a while with a groin injury so he wasn't quite ready for the full game. But he came on and he has made a difference with the penalty'.

'There was some relief when we finally made the breakthrough because, as the game wears on, it only takes a second to score a goal and QPR, with their massive support, were always going to give it a go at some point'.

QPR, owned by the hugely wealthy trio of Flavio Briatore, Bernie Ecclestone and Indian tycoon Lakshmi Mittal, spent much of the game holding out, but they almost took the game into extra-time when substitute Samuel Di Camine missed a golden chance in stoppage time.

Caretaker-manager Gareth Ainsworth said: 'I thought we might have nicked a draw there. We went a little bit cavalier towards the end, but it was a risk worth taking'.

'It would have been a fairytale, but they are the breaks and if it had gone in we would have had another thirty minutes, which might have been tough, but we would have liked to sneak it in'. -- AFP