Of the eight teams in action in Wednesday’s four Round of 16 matches at Turkey 2013 two are former champions, five are unbeaten – four of them having won two and drawn one – and three are outsiders who gave the big boys a run for their money in the group phase.All four ties look too close to call. Even Portugal, who are among the tournament favourites, will have their work cut out against a Ghana side that came back from the dead in the first round and have nothing to lose. Croatia, Colombia and Iraq find themselves in similar situations, having put together impressive campaigns so far, but they will be taking nothing for granted against quality opposition.The schedule 3 July (all times local) Round of 16 Portugal-Ghana, Kayseri, 18.00 Croatia-Chile, Bursa, 18.00 Colombia-Korea Republic, Trabzon, 21.00 Iraq-Paraguay, Antalya, 21.00Match of the day The proud FIFA U-20 World Cup records possessed by Portugal, back-to-back winners of the competition in 1989 and 1991, and 2009 champions Ghana is one of the factors that make this tie such an intriguing one. There is more to it than history, however. Both sides play enterprising, attack-minded football, with the Portuguese heading into the knockout phase as the highest scorers with ten goals. Five of them came in the biggest win of the tournament to date, against Cuba, while the livewire Bruma is the leading marksman at Turkey 2013 with five goals. Though those statistics will no doubt please coach Edgar Borges, he will also be concerned about the four goals his side shipped in their first two matches against Nigeria and Korea Republic.While A Seleção das Quinas are the favourites to progress, Ghana’s dramatic qualification, which came after they kicked off with two defeats, ought to serve as a warning to the European side. The Africans put four past USA in their final group match and then endured a nervous two-day wait before their place in the last 16 was confirmed, albeit by a narrow one-goal margin from Egypt. Ghana’s determination to progress from arguably the toughest section in the competition and the enthusiasm with which they celebrated their eventual qualification suggests they will be very awkward opponents for the Portuguese.Other highlights Like Portugal, Croatia were another European side to collect seven points from their three group matches, albeit with a little less flair. One thing in their favour, however, is the fact they will be relatively fresh for the tie with Chile, with coach Dinko Jelicic having rested nine first-teamers for their last outing against New Zealand. The Chileans are sure to show more than they did in the group stage, when they narrowly beat Egypt, drew with England and then lost to Iraq, but will need to be at their best to counter the aerial threat of the Balkan side.After a surprisingly slow start against Australia, Colombia slipped through the gears to win Group C and justify their tag as genuine title contenders. The reigning South American champions will be hoping Juan Quintero can maintain his form against Korea Republic, who lost momentum after making a bright start in their pool. The South Koreans also have a major injury worry, with star man Ryu Seungwoo a doubt for Wednesday evening’s game.Of the day’s four matches, the one involving Iraq and Paraguay, both of whom are undefeated, looks to be the most open. Unfancied before the tournament, the Iraqis were nothing short of a revelation in winning a tough section and are now looking to continue their fairy tale run. The Paraguayans are also full of heart after beating Mexico and drawing their two other Group D engagements, which was enough to give them second place. The absence through suspension of captain Gustavo Gomez, who was sent off against Greece, is nevertheless a major headache for La Albirroja.Player to watch While perhaps not reaching the levels expected of him, especially after helping himself to four goals at the South American U-20 Championships, the Paraguayan midfielder Derlis Gonzalez has what it takes to become his side’s go-to man in the knockout rounds. He proved his worth by getting the only goal of the group meeting with Mexico, his team’s only win to date. The Benfica man, who is currently on loan at Guarani, is not lacking in motivation, having promised to dedicate every goal he scores in Turkey to his newborn daughter.The number 57 - The number of shots Ghana have had on goal at Turkey 2013, the same as Nigeria and Mexico, followed by Portugal with 55, twice as many as the next team on the list. Some 29 of the Portuguese’s shots have been on target, two fewer than Colombia, who have had more than anyone else. Of all the teams in action on Wednesday, Korea Republic have registered the fewest shots, a