By Simon Evans
MANCHESTER, England (Reuters) - Fabian Delph and Ashley Young are not two names that, at the start of this season, would have been high on many lists of key players for the Manchester derby but with the wide areas likely to be a major battleground in Sunday's Premier League clash their roles will be vital.
Delph, a midfielder throughout his career, was forced into left-wingback duty when first choice Benjamin Mendy suffered a knee ligament injury in September and the 28-year-old has handled the new position with aplomb.
Young, who has been converted to fullback duty after making his name as a winger, has made the United left-back slot his own with impressive performances this season earning him a recall to the England squad at the age of 32 after a four-year absence.
With Antonio Valencia on the right flank, United have been able to develop a counter-attacking style down the flanks, allied to their attacking wide players such as Anthony Martial.
City's formation is similar, with Kyle Walker advancing with pace down the right, in alliance with Raheem Sterling, while Delph provides wide support to Leroy Sane on the opposite side.
Pep Guardiola's side often push their fullbacks so far forward that is questionable whether they can be considered defenders in any real sense.
The Spanish coach is aware that against United's counter-attack his team will need to be alert to the spaces in the wide areas that Jose Mourinho's side will look to exploit.
"You have to defend these areas, definitely. With fullbacks, attacking midfielders or holding midfielders or wingers, you have to close that space," said Guardiola.
"The teams from Jose Mourinho -- Chelsea, Real Madrid and here, they are the masters of that. When you lose the ball they are going to immediately counter-attack with Lukaku or make movements behind our full backs with Martial, (Marcus) Rashford or (Jesse) Lingard.
"You know if you are not well organised they punish you in one action and win the game," he said.
"They have the potential to run 30 metres and create problems. That space beside our centre-backs and behind our fullbacks is the space we have to be careful about, definitely," he added.
Guardiola, though, is not ready to sacrifice the attacking potency of Walker, a close-season signing from Tottenham.
"It depends on the players and if you have the energy of Kyle Walker, you have to attack with him," said Guardiola.
(Editing by Clare Fallon)