Fergie wary of paying penalty

David Silva will be given every chance to prove his fitness ahead of the Manchester derby at the Etihad Stadium.
The Spaniard missed the midweek loss to Borussia Dortmund in the Champions League with a hamstring injury but remains in contention and is battling to be ready.
Aleksandar Kolarov has been ruled out with a groin problem, while Mancini will continue to monitor the progress made by fellow injury victims Gael Clichy and James Milner.
Tom Cleverley is doubtful for Manchester United after limping out of the game against CFR Cluj and will have a scan on his calf injury.
Sir Alex Ferguson has also revealed that Shinji Kagawa and Nemanja Vidic, who have both suffered knee injuries, are struggling to be fit in time for the derby.
The likes of Robin van Persie and Patrice Evra are set to return to the starting line-up after being rested in midweek.
The number of penalties City get at the Etihad Stadium has been the subject of debate for the past two years.
Since the start of 2010-11, they have been awarded 21 spot-kicks.
In the past three games on home soil alone they have got four, two against Aston Villa and one each in the draws with Real Madrid and Everton.
And, ahead of his own side's visit to City on Sunday, Ferguson has cheekily raised the issue.
"The number of penalty kicks they get - 21 in the last year or something like that," said Ferguson.
"If we got that number of penalty kicks there'd be an inquiry in the House of Commons. There'd be a protest."
Bizarrely though, United have had more than City this season, only to miss four of them.
It piles the pressure on referee Martin Atkinson ahead of this weekend's game, which Ferguson accepts has risen markedly in profile since the days when he claimed Liverpool were United's true rivals.
"Liverpool and United games over the last 25 years have been unbelievable," said Ferguson.
"They've always been the most important games.
"It's shifted because at this moment Liverpool aren't challenging for the league like City are.
"City are our biggest threat and we're their biggest threat, so that's changed.
"Their fortunes changed the minute Sheikh Mansour took over.
"We know the minute that happened it was going to be a different ball game altogether.
"But, as we have in the past, we have to accept their challenge like we did when Chelsea came along and when Arsenal overtook Liverpool in the early 90s.
"We have to do it again."
Ferguson is still to discover whether Tom Cleverley will be fit after limping out of Wednesday's Champions League defeat to Cluj with a calf injury.
Antonio Valencia and Nani have already been ruled out, whilst faint hopes that both Shinji Kagawa and skipper Nemanja Vidic could be involved appear to have faded.
"I thought Kagawa may have done enough to make the bench on Wednesday but no, he's well short," said Ferguson.
"I don't think he'll be available until the Sunderland game next week.
"Nemanja Vidic is certainly doing well in training. It suits his own confidence to play but I think the game on Sunday is a bit soon for him.
"I think he'll also be ready for Sunderland."