The Sweden manager is well aware his contract is unlikely to be renewed if he fails to lead his country past the Seleccao.
The 56-year-old's contract expires after next summer's tournament in Brazil and, with his side 1-0 down after last week's first-leg clash with the Seleccao, he knows that the outcome of the return fixture will decide whether he is asked to stay on.
"It's happened to me a few times before as a club coach, when you know that if we lose a game there's not much left of the job," he said during a news conference Monday. "But I'm not thinking about that one bit. My focus is on succeeding, and if we do succeed we don't need to discuss it."
The tie has, of course, been billed as a straight shootout between Cristiano Ronaldo and Zlatan Ibrahimovic, with the former having drawn first blood by netting the only goal in Lisbon.
The pressure is, therefore, now on Ibrahimovic to strike back, but Hamren insists that the game is about more than two players.
"He [Zlatan] has been at this level for many, many years, and for us it's not Ronaldo versus Zlatan - it's Portugal v Sweden," Hamren said. "We need to score, that's for sure. [Portugal] can play more for the result. They have an advantage in that regard. We are meeting a really good team with really good international players, so we can't start the match and just go forward because then they're going to punish us quickly."
Sweden's eagerly awaited clash with Portugal in Solna is scheduled to kick off at 2:45 p.m. Eastern.