Nacional have been struggling lately, losing three of their last five matches, though they did manage a couple of wins on the road. Guimaraes have also had a tough time, losing three of their last five games and winning only twice. When these two teams have met in the past, there have often been quite a few goals, with several matches ending with three or more total goals. This looks like a fairly close match between two sides that are not in great form, so it could go either way. I think a draw is the most likely outcome here.