The national team coach has voiced his disappointment with his side's defeat in Lisbon, but has stressed they will do their utmost to make amends in the return fixture in Solna
A single Cristiano Ronaldo goal in the closing stages of the game saw the Scandinavians leave Lisbon empty-handed, yet their 56-year-old coach remains hopeful that they can turn things around in Solna.
"Portugal pushed more in the second half and we were forced to play too many balls in the air," Hamren told reporters.
"The goal we conceded was a bit sloppy. I'm always disappointed when we lose, but I would have been really happy with the draw.
"We must work hard [in the second leg]. I hope we will play better at home.
"After this we must win the next game at all costs. We will do everything we can to win."
The second leg takes place at the Friends Arena on November 19.