RIGA (REUTERS) - Portugal's Cristiano Ronaldo scored twice, taking his tally in the World Cup qualifiers to 11 goals, to help them claim a somewhat flattering but important 3-0 win away to Latvia on Friday.

Portugal's fifth successive win in Group B left them with 15 points from six games, but still three behind leaders Switzerland who beat Faroe Islands 2-0 to maintain their 100 per cent record. Ronaldo, Portugal's all-time leading scorer, took his tally to 73 goals for his country after another decisive performance.

He looked their only real threat in the first half and scored four minutes before half-time when he stooped to head in from close range after Jose Fonte's header hit the post.

Ronaldo scored with another easy header in the 63rd after Ricardo Quaresma's cross was deflected into his path, and then played a one-two with Andre Silva who scored the third four minutes later.

The group looks increasingly like it will boil down to the final match between Portugal and Switzerland in October which the European champions must win to top the standings, qualify directly and avoid a perilous two-leg play-off.