Wigan manager Roberto Martinez has hailed the impact Paulo Bento has had since his appointment as Portugal manager.The former Sporting Lisbon boss was named as Portugal's head coach in September 2010, and has since gone on to win 60 percent of his 20 games in charge, including a 4-0 win over Iberian rivals Spain.And Martinez feels that his colleague deserves all the credit possible for his good work, following the team's qualification for the Euro 2012 semi-finals."I am really impressed with Portugal," Martinez told UEFA.com."I am fascinated how Paulo Bento has found the perfect, winning formula for Portugal. He deserves huge credit, it was a very astute tactical change to free (Cristiano) Ronaldo and allow all the good play."Martinez complimented how Bento has set up the midfield, as they anchor and provide support to wide players Nani and Ronaldo."For me, the strength of that group is the midfield three - (Miguel) Veloso, (Joao) Moutinho and (Raul) Meireles."I think they give a fantastic balance and they are a really good combination but obviously, in any team, you need to score goals. That comes from Cristiano Ronaldo."He can afford just to appear in the game and be very effective because he is completely free, he starts on the left-hand side but he'll come through the middle, play in between lines and get in behind people."You'll see him having one-on-ones everywhere on the pitch. They are very strong as a team but they can rely on one of the best players of his generation, in Cristiano Ronaldo."Portugal meet Spain in the semi-finals of Euro 2012 on Wednesday.