Xavi believes the Seleccao are not to be underestimated and praised a number of the midfield threats that will line-up for Paulo Bento's team.
"They’re a great side," Xavi told Fifa.com. "Not just Cristiano, who’s an attacker you constantly need to keep an eye on, of course, but Nani as well and good footballers like Joao Moutinho and Raul Meireles.
"They're both very skilful and can move the ball around quickly. They’re a tough team and, on top of that, they're very tight at the back very well. It’s going to be tricky."
|THE MAIN MAN?
|7/1||Xavi is 7/1 to be the man of the match when Spain take on Portugal with William Hill|
"Spain have improved with each game and have shown their competitiveness," Xavi stated. "We know how to perform in these situations.
"Sometimes we can’t always play well, but the important thing is that even then we remain tough opponents. We all help each other out as a team, and that shows on the pitch."
Wednesday's semi-final encounter kicks off at 20:45CET.