Cristiano Ronaldo was put through his paces during a Portugal training session as they prepare to face Serbia in a crunch Euro 2016 qualifier on Sunday . Portugal host their European rivals knowing a victory would stretch the gap over Serbia to eight points after four matches . Despite the importance of the tie , with Denmark currently sitting top of Group I with seven points , Ronaldo and his team-mates seemed in good spirits . Cristiano Ronaldo ( right ) was put through his paces by manager Fernando Santos during Portugal training . Ronaldo ( left ) smiles with Portugal team-mates including Real Madrid defender Pepe ( middle ) The Real Madrid striker has been in fine form for his club this year and has scored an impressive 31 La Liga goals in 25 matches . However , the former Manchester United player will be aiming to put last Sunday 's El Clasico defeat by Barcelona behind him . Ronaldo was on the scoresheet at the Nou Camp when he equalised after Jeremy Mathieu had opened the scoring but Luis Suarez 's winner secured a 2-1 victory for Barcelona . The Los Blancos star has scored 31 La Liga goals in 25 matches this season for his club . The 30-year-old seemed in high spirits during training despite the importance of Sunday 's clash with Serbia . Portugal have endured an indifferent Euro 2016 qualifying campaign so far after losing their opening fixture at home against Albania . But victories against Denmark and Armenia leaves them in second spot and a win on Sunday would stretch their gap over Serbia to eight points after four matches . Ronaldo takes a break from training with Fabio Coentrao ( centre )
Portugal face Serbia on this season in crucial Euro 2016 Group I clash . Victory for Portugal would see them move up to nine points . Cristiano Ronaldo has scored 31 La Liga goals in 25 matches Sunday . READ : Ronaldo back in action for Portugal ahead of Euro 2016 qualifier . WATCH : Ronaldo pranks Portugal team-mate Ricardo Quaresma .