Cristiano Ronaldo is back on Portugal duty this week ahead of his country 's crunch Euro 2016 qualifier clash against Serbia on Sunday night . Ronaldo was in the thick of the action at training following Real Madrid 's 'El Clasico ' defeat by Barcelona on Sunday night . The Catalans opened up a four-point lead over their arch rivals at the top of La Liga following their 2-1 victory at the Nou Camp . Cristiano Ronaldo ( centre ) takes on Ricardo Quaresma ( left ) and Vieirinha during training on Wednesday . Ronaldo has a chat with Portugul head coach Fernando Santos during the session in Lisbon . Ronaldo was waering his signature model Mercurial Superfly boots during the training session . The Los Blancos star will have to put that defeat to the back of his mind , however , as Fernando Santos ' side gear up for the visit of Serbia . Ronaldo looked focused during his side 's training session at their team base in Lisbon joining fellow team-mates Pepe , Ricardo Quaresma and Vieirinha . Portugal got their Group I campaign off to an awful start when they were lost 1-0 at home to Albania last September before bouncing back with a 1-0 victory against Denmark the following month . Portugal and Real Madrid centre back Pepe controls the ball as the Portugal coaching staff watch on . A narrow 1-0 win against Armenia in November has revived Portugal 's Euro bid as they look to keep pace with the Danes at the summit of the group . Victory for Portugal on Sunday would stretch their gap over Serbia to eight points after four matches .
Portugal host Serbia in their Barcelona I fixture in Lisbon on Sunday night . Denmark currently sit top of the Barcelona on seven points . Victory for Portugal on Sunday would stretch their gap over Serbia to eight points after four matches .