The 25-year-old has caught the eye at the World Cup having found the net three times in Ecuador’s opening two outings in Brazil, including both goals in the 2-1 win over Honduras.
Valencia was also on target in his country’s 2-2 warm-up draw with England ahead of the tournament, and now the likes of Newcastle, Everton and Tottenham have been reported to be monitoring his situation.
Valencia only joined Pachuca at the start of 2014, where he has scored 18 times in 23 games, but Andres Fassi says there has already been interest.
"Enner Valencia’s value increases every day. We don’t know if he will stay, it will be hard given the offers we have received," he told Mexican ESPN.
"The options that a great player at this level gets are to be taken into account. But for now he has to keep doing things right.
"No doubt it would hurt us to let Enner Valencia go, but we are realistic about his quality."
Porto have also been linked to Valencia, but Fassi was keen not to fuel speculation as he wants the striker to continue thriving in Brazil.
"I don’t want to name a team, we want to respect the sporting moment of the player and of his national team."