July 3 (Reuters) - Portugal's place in the World Cup last 16 has brought relief rather than euphoria, with Roberto Martinez's side through after victory over Croatia but still struggling to match the expectations that followed them into the tournament.
Led by Cristiano Ronaldo and billed as one of the main contenders, they have looked more functional than frightening, mixing quality with the inconsistency that left them runners-up behind Colombia in Group K after two draws in three matches.
Their laboured 2-1 win over Croatia secured progress but did little to silence concerns back home, where performances from leading players such as midfielders Vitinha and Bruno Fernandes have come under scrutiny.
Ronaldo netted a penalty for his first World Cup knockout-stage goal, extending for at least one more match what could be his Portugal farewell after his sister suggested in an interview he would retire from the national team after the tournament.
Yet the 41-year-old's role as an almost untouchable figure remains a source of unease among some supporters and sections of the Portuguese media.
Ronaldo was substituted in the second half against Croatia and appeared to give Spaniard Martinez an unhappy look as he left the pitch, adding another layer to the debate over how Portugal should use their captain in the knockout stage.
"The national team is a group of players who are still striving to become a proper team," Portuguese newspaper Record headlined.
That search for cohesion now faces a severe examination.
Portugal next meet European champions Spain in the round of 16 on Monday, a tie that offers Martinez's side the chance to transform a campaign of doubts into one of genuine momentum.
(Reporting by Fernando Kallas; Editing by Ken Ferris)
