Lautaro Martinez is almost certain to join Atletico Madrid, his agent has said. Getty

Atletico Madrid are closing in on the signing of Argentina under-20 striker Lautaro Martinez from Racing Club, his agent has said.

Rolando Zarate said Racing had accepted an €11 million offer for the 20-year-old -- €2m higher than his buyout clause.

However, Martinez will not arrive at Atletico until next summer after asking to stay for another season at Racing.

"There is a 99 percent chance that the deal will be done," Zarate told Fox Sports Argentina.

"Lautaro asked us expressly for the transfer to be nailed down. He likes the idea of Atletico Madrid and they have agreed to it.

"He wants to remain for another season because he wants to play the Copa Libertadores with Racing."

Atletico cannot register new players until January 2018 when their transfer ban ends.

Martinez scored nine goals in 23 league appearances to help Racing finish fourth in the Primera Division last season and qualify for the Libertadores group stages.

Racing president Victor Blanco had voiced fears that his club would lose the striker, saying earlier this month: "If it were up to me I would increase his release clause to €40m because he is worth that."

Reports in Argentina suggested Martinez had also been monitored by Real Madrid, but Atletico were the leading contenders to buy him.