The suspended coach had to watch the game from the stands, but was delighted with the way his side responded.
"We had a lot of courage, had good combinations, moved well without the ball - all the things that we've done well in the past we did," he said.
"Sitting behind the window in the stands was really difficult. It is too far from the action."
The 48-year-old Low gambled by making three changes to his midfield, but it paid off with Bastian Schweinsteiger scoring once and setting up the other two goals in the 3-2 win.
Low added: "After the Austria match we saw we had to make some changes. We wanted to close down the space in Portugal's midfield. We succeeded in doing that."
"We changed the system a bit with five in midfield and one striker less, we were very compact.
"Especially in the first half I thought we played fantastically against a very strong Portugal team until now. I think we deserved it."