Cristiano Ronaldo struck a double as Portugal kept their World Cup qualification hopes on course with a 3-0 victory over Hungary in a one-sided Group B clash in Lisbon.

The Real Madrid forward rifled in his first as part of a four-minute goal blitz in the first period after Andre Silva had broken the visitors' resistance with a neat opener just past the half hour.

Ronaldo then crashed home a trademark free kick in the second half to seal the win and take his overall tally for his country to 70.

The European champions knew they could not afford any slip after leaders Switzerland had maintained their 100 per cent record with a 1-0 success over Latvia earlier in the evening - and they responded after a slow start to comfortably consolidate second spot in the pool.

Fernando Santos' men are now five points clear of third-placed Hungary and just three behind the Swiss, with only the side finishing at the summit guaranteed a place at next year's finals in Russia.