Cristiano Ronaldo declared "I'm back" and said criticism of him and his Portugal team-mates was unwarranted after getting their World Cup campaign up and running on Tuesday.

Ronaldo made World Cup history during Portugal's 5-0 thrashing of Uzbekistan, becoming the first player to score at six different editions of FIFA's flagship competition. 

The 41-year-old opened the scoring in the sixth minute at Houston Stadium with a smart finish from Joao Cancelo's teasing delivery to the near post, with Nuno Mendes' free-kick doubling Portugal's tally 11 minutes later. 

It was 3-0 six minutes before half-time when Ronaldo finished past Abduvokhid Nematov, with the Uzbekistan goalkeeper then scoring an own goal on the hour mark. 

Rafael Leao sealed the win three minutes from time, but the day belonged to Ronaldo, who has now scored 10 goals at the World Cup, the most of any Portugal player, ahead of Eusebio (nine).

Coming into their clash with Uzbekistan, Ronaldo had failed to score in each of his last 10 major tournament (World Cup/EURO) appearances, despite attempting 33 shots and amassing an expected goals (xG) total of 4.5 in those games.

Ronaldo shouted into a television camera, "I'm back, I'm back" following the full-time whistle, and the five-time Ballon d'Or winner was relieved that he could play a part in Portugal's response to their draw with DR Congo in their opening group match. 

"I can say it was a very tough week, a difficult week, a week in which public opinion was very harsh on us, on all the players, especially on the coach," Ronaldo said. "But it's always like that.

"It's fine because when you think about it, it's already 23 years since I've been a professional and whenever things don't go well it's, 'Cristiano, he's finished, he's old'.

"But well, it was a good response from me and my teammates, which is what we wanted."

Ronaldo also became the second-oldest scorer in World Cup history (41 years, 138 days), behind Roger Milla in 1994 for Cameroon against Russia (42 years, 39 days), while he is the oldest European player to score a goal in a major tournament (EURO/World Cup).

It saw the Portugal captain join the party at the World Cup, with the likes of Lionel Messi, Kylian Mbappe and Erling Haaland all starting their respective campaigns with goals in their first two appearances at this year's tournament. 

Portugal coach Roberto Martinez believes Ronaldo's rivalry with the Argentina captain Messi is important for ​both players, and is what drives them to stay at their best.

"I believe both players have improved football over the years and their rivalry is important for themselves to grow," Martinez added. 

"[Ronaldo] is an icon and a ​role model in the national team. He has a great attitude on the pitch and in ​the dressing room.

"Not just the scoring, the passes, the chances created, he is a role model when it comes ‌to ⁠the World Cup."

For Uzbekistan, meanwhile, their World Cup debut has not gone according to plan, though they do remain in with a shot of reaching the knockout stages despite losing both of their group games so far. 

However, they did become the fifth consecutive debuting Asian nation to lose both of their opening two matches at their first ever World Cup tournament, after Japan (1998), China (2002), Qatar (2022), and Jordan (2026).

Uzbekistan thought they had halved the arrears with a rocket of a strike from Aziz G'aniev, only for a VAR review to cut their celebrations short after Abbosbek Fayzullaev's foul, though head coach Fabio Cannavaro took full responsibility for his team's defeat. 

"They tried everything, they ​tried their best. I am very proud," Cannavaro told reporters. "We have to keep believing until we mathematically cannot go through.

"All my life I ​have taken responsibility, as a player and as a coach. If we lost 5-0, it is ‌because ⁠today I made mistakes, and not them [the players]. 

"This is our first time at the World Cup. I told the players that they can misplace a pass and make mistakes. Because I must give them the confidence to try and ​improve.