The Eredivisie\'s leading duo will face a stiff examination of their title credentials with difficult away games this weekend. Leaders AZ Alkmaar head to sixth-placed Heerenveen, while second-placed PSV Eindhoven are at fifth-placed Feyenoord. To add to the challenge, both head into the weekend on the back of away games in Europe in midweek, with PSV back from a 3-0 win over Legia Warsaw, while AZ drew 0-0 at Malmo. PSV\'s task is the toughest, as they head to a stadium where they have only won ten of their last 55 matches, and only four of their last 25. However, two of those wins are in the last two years, so perhaps the tide is turning. AZ head to Heerenveen without the suspended Pontus Wernbloom, but Erik Falkenburg, who filled in impressively for him in Sweden, is not sure if he will get the nod again. \"That could be,\" he told the club\'s website. \"But now I just want to recover from this game. It is hard to look ahead to Sunday.\" Regardless of what happens in their matches, neither of the top two can be caught by FC Twente, who can only hope to cut the gap to second to a single point when they travel to FC Utrecht on Sunday. Ajax will hope to close their own now considerable gap to the top - ten points going into the weekend - when they host Excelsior on Saturday. Captain Jan Vertonghen hopes the focus on off-the-field matters can actually help them turn their season around. \"The media has been focused on the administrative turmoil, which meant they didn\'t spend as much time on our performance dip,\" he said in Voetbal International. \"This can help the younger players who are under a lot of pressure. We can work in relative peace for a change.\" Excelsior are in much deeper trouble, outside the automatic drop zone on goal difference alone, above VVV Venlo who open the weekend\'s action when they travel to Heracles Almelo tomorrow. De Graafschap could escape the relegation play-off places with victory over Roda JC, although they would require help from FC Groningen, who face struggling NEC. ADO host NAC Breda while RKC Waalwijk travel to Vitesse Arnhem.