Portugal played their quarter-final against Czech Republic on Thursday, while Spain's last-eight match against France was on Saturday and Minano said that would give the Portuguese "something of an advantage" over the holders in Donetsk.
"There is no doubt that it has an impact but then again we had a day longer than the French to prepare for the quarter-final so we can't use it as an excuse either," he added in a rare appearance at a news conference at Spain's training base in Gniewino, northern Poland.
Like all the other national teams competing in Poland and Ukraine, the Spanish players have endured a long, hard season with their clubs and Minano said it was impossible to tell whether they were close to their physical limit.
"A few years ago it was unthinkable that a player could play 5,000 minutes of football in a season, which is the case with some of these footballers," he added.
"It's a challenge for them no doubt but it's the same for other teams and the response has been good.
"Based on that response, the coach is picking the players who he believes can perform the best."
Spain had yet to decide whether they will return to Gniewino after the semi-final if they get through to the final on July 1 in Kiev, or whether they will head directly to the Ukrainian capital, Minano added.
"The calm and the excellent facilities we have found here [in Gniewino] will certainly play a major role in the decision," he said.
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.