Manchester United could find themselves in a tug-of-war with derby rivals Manchester City on the final day of the transfer window over Porto defender Nicolas Otamendi.

According to reports from Duncan Castles, The Red Devils have lodged a £12.3 million bid for Porto’s central defender Nicolas Otamendi, but the Portuguese club have yet to make a decision whether to sell him.

The 25-year-old has been at Porto since 2010 and was a key member of Andre Villas-Boas’ side that won the treble.

However, Manchester United’s bid for the player is largely complicated by Manchester City’s attempt to sign another Porto defender Eliaquim Mangala.

According to reports from The Times, City are prepared to dish out a sum, more than 30m for the French defender, but Porto intend to retain him for the rest of the season.

The Times further reports that if City fail to reach an agreement for Mangala, they will switch their attention to Otamendi which could further complicate the situation.