Portugal head coach Fernando Santos jumped to the defence of his experienced side after they cruised past Luxembourg 5-0 in their World Cup qualifier thanks to Cristiano Ronaldo.

Ronaldo's 58th career hat-trick and 10th international treble put hosts Portugal out of sight at the Estadio Algarve, where Joao Palhinha and Bruno Fernandes also got on the scoresheet on Tuesday.

The five-goal crushing left Portugal a point behind Group A leaders Serbia, albeit with a game in hand, with two matches remaining and the top two teams meet on the final matchday, in what is likely to be a winner-takes-all decider.

However, Santos' focus after the game was on the age of his squad as he quashed suggestions that his veterans were likely to let him down again, after exiting both the 2018 World Cup and Euro 2020 at the last-16 stage.

"I hear a lot about it [the age of the squad], I even understand, but more changes than what we have been done over the past six years are difficult," Santos told reporters during his post-match his news conference, with set to be 37 heading into next year's World Cup.

"Just look at who was at the World [Cup], the European Championship and who is playing now. There are no age restrictions, it doesn't even make sense.

"Players do not have to stop playing for the national team because they are of more or less age, quality is what counts. 

"Fortunately, we have a lot of 30-year-old or 31-year-old players able to get here and play and the players have shown that [quality]."

Portugal will have to wait until November's international break to seal their fate and Santos appreciates the decisive nature of the Serbia clash while imploring his side to still improve.

"We managed to restrain the opponent and take advantage of every situation to transform them into goalscoring opportunities," he told RTP after the game.

"We did very well until the 25th minute, with how we played and what we had seen from Luxembourg.

"After that we also did well, but we started to want to do everything in a hurry, in one touch, two touches, and we even allowed Luxembourg to get ahead.

"The last game will be decisive, whatever happens in the next round, neither team will be out, although I believe we will win [against the Republic of Ireland] – it will be decisive."

Cristiano Ronaldo scored a hat-trick as Portugal cruised past Luxembourg 5-0 in Tuesday's World Cup qualifying clash.

Ronaldo took just eight minutes to open the scoring at the Estadio Algarve as he finished from the penalty spot before doubling his tally soon after in the same fashion.

Bruno Fernandes netted a third inside a decisive opening 20 minutes before the Manchester United playmaker assisted Joao Palhinha for the fourth in the second half.

Ronaldo then secured his hat-trick with three minutes remaining to cap the hosts' dominant performance and ensure they remain a point behind Group A leaders Serbia – who have played a game more – ahead of the next international break.

Sebastien Thill and Anthony Moris were the guilty parties for the early penalties with fouls on Bernardo Silva and Ronaldo, the latter clinically converting both.

Things went from bad to worse for the visitors as Fernandes made it 3-0 despite Moris getting a hand to his right-footed drive following Silva's throughball after 17 minutes.

Ronaldo almost claimed his hat-trick on the stroke of half-time but was denied by Moris, who also saved Silva's acrobatic volley.

Danel Sinani brought a rare save from Rui Patricio, with both Palhinha and Fernandes missing the target at the other end after being found by Nuno Mendes' searching deliveries.

Ronaldo's overhead-kick deserved to complete his treble, but Moris tipped over before Palhinha headed home from Fernandes' resulting corner.

Luxembourg almost grabbed a consolation goal through Gerson Rodrigues, but his left-footed strike was turned away by Patricio and Ronaldo completed the scoring as he headed in from Ruben Neves' deep cross.

Joao Felix is not expected to be a combative player for Portugal, but Fernando Santos suggested the Atletico Madrid star must do more to stand out.

Portugal came from behind to beat Luxembourg 3-1 on Tuesday, moving top of World Cup qualifying Group A in the process.

Gerson Rodrigues scored his second goal in as many games to put Luxembourg ahead, but Diogo Jota, Cristiano Ronaldo and substitute Joao Palhinha sealed the points for Portugal.

Jota's equaliser – a header from inside the six-yard box – was teed up by the Liverpool forward's former Wolves team-mate Pedro Neto, who replaced Joao Felix in the 41st minute.

Making his first start of the qualifying campaign, Joao Felix appeared to be struggling with an injury to his right ankle, seemingly sustained when he had a shot blocked in Luxembourg's box.

It was the youngster's only attempt, while he also failed to create a chance and completed just 18 of 25 attempted passes.

Neto, on the other hand, ended the match with two assists, for Jota and Palhinha respectively, and it was a performance that drew the praise of Santos, who hinted that it is difficult to fit Joao Felix into a certain role in his team.

"Neto had different movement, another dynamic, he looked for depth, he went looking for the ball," Santos told reporters.

"He always participated in defensive actions. Joao always had more difficulty. He has his own way of playing, he is not a combative player, we are not expecting that either.

"He has a lot of technical quality, he has the quality to make a difference, but we all have to be together so that these things can work."

It is an issue that has also stymied Joao Felix's Atleti career to date, with the 21-year-old delivering some quality displays at the start of the campaign, but scoring just twice in LaLiga since the turn of the year.

Ronaldo's goal was his 103rd for Portugal, taking the 36-year-old to within six strikes of Iran legend Ali Daei's record, while he has also scored in every calendar year since making his international debut in 2004.

The Juventus star squandered two gilt-edged chances to double his tally at 2-1, in what was a rather laboured performance from the reigning European champions, and Santos acknowledged he has to strike a balance between playing to the strengths of the attacking talent he has available, while also remaining organised.

"Technical quality alone doesn't win here, if we don't balance these important factors," he added. 

"It's not that the players don't want to. We had difficulties. But then there was an instant reaction, we scored in an important moment.

"The second half was [better]. The goals appeared and we could have scored more. We had opportunities."

Cristiano Ronaldo edged closer to Ali Daei's international goals record as he opened his account for the World Cup qualifying campaign in Portugal's 3-1 comeback win over Luxembourg.

Ronaldo had a last-gasp winner disallowed against Serbia on Saturday, but the Juventus star had no need to throw his captain's armband to the floor in anger this time around, nudging home to make it 2-1 to Portugal five minutes into the second half.

Fresh from his goal in Luxembourg's victory over the Republic of Ireland, Gerson Rodrigues had put the minnows – who had Maxime Chanot sent off late on – ahead with a smart header.

Diogo Jota levelled proceedings on the cusp of half-time to pave the way for Ronaldo's 103rd international goal and Joao Palhinha's header to send Portugal top of Group A.

Cristiano Ronaldo will not be stripped of the Portugal captaincy after his "moment of great frustration" in the closing stages of Saturday's controversial draw with Serbia, head coach Fernando Santos has insisted.

Ronaldo was convinced his last-gasp effort crossed the line, but the officials disagreed as Serbia rallied from two goals down to secure a 2-2 draw in World Cup qualifying.

Stefan Mitrovic made back-to-back goal-line clearances to thwart Portugal in stoppage time, though Ronaldo was adamant his effort crossed the line in Belgrade, where there was no VAR in place to review the decision.

Ronaldo was booked for his protestations before he angrily threw his captain's armband on the floor and walked off the field with just seconds remaining.

Santos revealed after the game that "embarrassed" referee Danny Makkelie had apologised upon reviewing footage of the incident. 

While Santos accepts Ronaldo should not have behaved the way he did, the Portugal boss has no intention of taking the captain's armband away from his talisman ahead of Tuesday's Group A clash with Luxembourg. 

"He will keep the armband," Santos told a media conference. "If he had offended the coach, his colleagues or the federation, then yes, we would have to think. Nothing like that happened. 

"What happened was a moment of great frustration that could have happened to me. Frustration of someone who always wants to win, who gives everything for the national team. It happened to him, it could have been someone else. 

"He was the first to recognise that he should not have done it. He will be captain for sure."

Midfielder Ruben Neves spoke alongside Santos on Monday and hailed Ronaldo as an "exemplary captain". 

"He did not apologise and he does not have to," the Wolves man said. "He is an exemplary captain for everyone. 

"We all felt the frustration he felt at that moment; it was a difficult moment for everyone. We know Ronaldo very well and we know what he can give us every day."

Portugal are level with Serbia on four points atop Group A, one point ahead of Luxembourg after their stunning win over the Republic of Ireland.