Wigan manager Roberto Martinez believes striker Victor Moses could be affected by speculation surrounding a
potential transfer to Chelsea.
Chelsea have been trying to sign the 21-year-old all summer, but have yet to meet Wigan's £8.5m valuation.
Crystal Palace, Wigan
Nigerian (3 caps)
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Moses played for England at Under-16, U17, U19 and U21 level before pledging his allegiance to Nigeria.
"If you don't meet a valuation, it becomes paper talk and speculation," he said.
"It happens everywhere, it gives you uncertainty and I don't think that helps. The players are human beings."
Nigerian international Moses scored six goals for the Latics last season, playing a key part in their successful bid to stay in the Premier League.
Chelsea have made two cash bids for the winger, who has a year left on his contract, but both have fallen some way short of Wigan's valuation.
And Martinez still retains hope of keeping the forward at the DW Stadium.
"For Victor it's been an exciting summer," said Martinez. "I told him he should be very proud, as a footballer at 21, to get the interest he has had.
"Victor knows what he did from December to the end of the season was a great level of performance.
"He can take it on to the next level and I am very excited to have Victor at Wigan, and I hope we can keep him for many years to come."
Chelsea visit Wigan on Sunday, and Martinez believes the transfer window should be closed during the season to avoid players becoming distracted.
"I don't agree with the transfer window going on while there are official games," he added.
"I do feel there is a need for a transfer window, it is beneficial, but I don't think it helps when it is open when you are playing official games."