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Barcelona's ability to offer Lionel Messi an improved contract will rest on their capacity to raise revenue from sponsorship deals and player sales, chief executive Oscar Grau says.

Messi's contract expires in 2018 and he is expected to command a new deal on a par with the reported £21m a year earned by Luis Suarez and Neymar.

But La Liga's salary cap means Barca must exercise common sense, Grau said.

"We want the best players but perhaps we have to prioritise," he added.