Borussia Dortmund sporting director Michael Zorc has revealed that the club could still keep striker Robert Lewandowski for another season, even though it would mean losing him on a free transfer. Lewandowski, whose contract expires in the summer of 2014, has been strongly linked to both Manchester United and Bayern Munich.

United targeted the 24-year-old last summer before they secured a deal for Robin van Persie, but there has been much speculation that they remain keen on the player. However, Sky Italia claimed last month that Bayern Munich had already agreed to terms with Lewandowski to take him to the Allianz Arena at the end of the season.

It is widely believed that Dortmund will be forced to cash in on the Poland international this summer, but Zorc has said that is not seriously the case.

“Robert is one of the best strikers in Europe," he told German tabloid Bild. "It is extremely difficult to replace him. In the three years with us, he has become a world class player.

"Why can't we have one more season with Lewandowski?"

Another long-standing Manchester United target is also involved in recent speculation. According to the Daily Mail, United could use both Nani and Anderson as part of a part-exchange deal to secure Porto winger James Rodriguez.

The highly-rated Colombia international is believed to have been scouted on numerous occasions, but Porto’s valuation of the player has often been cited as a stumbling block. But with Nani out of contract in 2014 and Anderson still failing to command a regular first-team place, both could head back to Portugal this summer. Indeed Anderson has suggested that a return to Porto, from where he joined United in 2007, could appeal.

“Porto are the one club I would consider moving back to Portugal for,” he said, according to the Daily Mail. “My past is there. It is where I put down my roots in Portuguese football.”

Manchester United could also look to reinforce their defense this summer, with Rio Ferdinand’s contract set to expire at the end of the season and doubts persisting about the fitness of Nemanja Vidic.

The Daily Mirror has reported that United will battle it out with Liverpool for the signing of Vasco de Gama’s Dede. The 24-year-old is thought to have been tracked by United for some time, but Vasco have now revealed that they need to sell Dede this summer to ease their debts.

A Brazil international, Dede is likely to cost in excess of £15 million, while any deal would also be complicated by the fact that he is more than half owned by a third party. Juventus and Benfica are also reported to have made inquiries for the player and Vasco have said that his departure is now imminent.

“We can’t mislead the fans, we will find it very difficult to hold on to Dede because the club needs the resources, and at some point it will happen—by the middle of the year,” said Vasco director general Cristiano Koehler.

“The desire of all is that he stays, but we have to prioritize the payment of wages, taxes and federal agreements, so it is inevitable we will have to sell - so it is possible, in the middle of the year when the sale goes through, we can use the money to restructure the club and make it safe.”

Another leading defensive target is believed to be Benfica’s Ezequiel Garay. According to TalkSport, reports in Portugal now suggest that United will have to compete with Chelsea for the Argentina international’s signature this summer.

Garay, 26, is said to be available for around £15 million.