The Ecuador striker Enner Valencia is undergoing a medical at West Ham United as Sam Allardyce looks to complete his fifth signing of the summer.

Valencia scored all three of his country’s World Cup goals in Brazil, attracting the attention of a number of Premier League suitors in the process, but it now appears that West Ham have won the race to sign the 25-year-old.

Although any fee is likely to remain undisclosed – the chairman of Pachuca, Jesús Martínez, has insisted Valencia will not be allowed to leave the club for anything less than a Mexican league record.

It has been reported the Hammers would pay a fee close to the club-record £15m total paid for fellow forward Andy Carroll last summer and Martínez was quoted last week as saying he wants any deal to include clauses that would see Pachuca benefit if Valencia was to move on.

“There are various offers for Enner Valencia, the strongest and closest to what the player and us are demanding is from a club from England,” he told Ecuagol. “I won’t talk about prices, but if he is sold, it will be the highest transfer fee ever in Mexican football, otherwise he won’t be sold.

“We are seeking the possibility that is convenient for him and the club and that he is sold for the price that we like. We want to keep a percentage of the player in case he is sold in the future to another big team in Europe.

“It hurts me, I don’t want to sell him and neither does the manager or the fans but we can’t go against the career the kid aspires to.”

Allardyce will be hoping that if Valencia is brought in he can prove stiff competition with Carroll for the main striker’s berth in his side. The England international missed a large part of last season with a troublesome foot injury and the Hammers struggled to score goals in his absence.

But, with the Argentina forward Mauro Zárate one of four players already acquired by West Ham this summer, their options in attack will be much-improved when their season kicks off at home to Tottenham.