Day five at the World Cup saw a couple of the big boys make their first appearance of the tournament, with Brazil and Portugal both entering the fray.
In the first game of the day, Breel Embolo scored the winner against the nation of his birth to give Switzerland a 1-0 victory over Cameroon.
At the Education City Stadium, Uruguay and South Korea played out yet another goalless draw, the fourth of the tournament.
Cristiano Ronaldo then became the first player in history to score at five different World Cup editions, helping Portugal to overcome Ghana in a five-goal thriller in Doha.
Brazil rounded off Thursday's fixtures, finally breaking through a stubborn Serbia side to get their World Cup off to a winning start with a 2-0 triumph.
Switzerland 1-0 Cameroon: Embolo strike continues impressive record in World Cup openers
Embolo's 48th-minute winner makes it six unbeaten for Switzerland in their first games of a World Cup, last tasting defeat in their tournament opener in 1966 against Germany.
The striker's tap-in early in the second half means he has now scored in his last three games for Switzerland, his best run for his national team since making his debut in 2015.
Xherdan Shaqiri laid the ball on a plate for Embolo to finish, and the former Liverpool man has now been directly involved in exactly half of Switzerland's 24 goals across their last four major tournaments, scoring eight and assisting four.
Cameroon's dismal World Cup record continues, making it eight straight losses stretching all the way back to 2002. Only Mexico recorded more consecutive defeats at the tournament, with nine in a row between 1930 and 1958.
Switzerland could count on an experienced line-up against Cameroon, with the average age of 28 years and 238 days among their starting XI their second-oldest in a World Cup game, only surpassed in 1950 against Brazil (28 years and 314 days).
Uruguay 0-0 South Korea: Group H rivals cancel each other out
Uruguay and South Korea became the seventh and eighth teams to start their 2022 World Cup campaign with a goalless stalemate, the most ever in a single edition of a tournament.
It is a familiar scoreline for Uruguay, with only England (16 per cent) having a higher share of goalless draws at the World Cup than their 14 per cent among teams with over 50 games at the tournament.
Three of Uruguay's last six World Cup competitions have started with a 0-0 draw, though they have now lost just three of their 14 opening games at the competition.
The two nations combined for just one shot on target, despite amassing 17 shots between them. On only one occasion since 1966 have more attempts been recorded in a game with only one on target, with Denmark and Scotland amassing 27 shots in 1986.
Diego Godin became his country's oldest World Cup player at 36 years and 281 days and he marked the milestone with another clean sheet, with Uruguay last conceding in the group stage of the tournament in 2014, when Wayne Rooney scored against them for England.
Portugal 3-2 Ghana: Ronaldo's record-setting goal helps Selecao edge thriller
This game was goalless with under half an hour to play, but it sparked into life when Ronaldo struck from the spot to become the first player ever to strike at five World Cup tournaments, scoring every at every edition between 2006 and 2022.
At 37 years and 292 days, Ronaldo became the second oldest World Cup goalscorer ever behind Roger Milla (42 years, 39 days), while he is also now both the oldest and youngest player to net for Portugal at the tournament.
Andre Ayew, now Ghana's second-top scorer in their competition history with three goals, levelled for the Black Stars, but Portugal roared back to win their opening game in a World Cup campaign for the first time in four attempts.
While Ghana became the third African side to score in six straight World Cup matches, their disappointing defeat means they are without a win in their last five matches at the competition.
Bruno Fernandes played an important part in his side's victory, becoming just the second Portugal player to register two assists in a World Cup match since Jose Torres against Brazil in 1966.
Brazil 2-0 Serbia: Scintillating second-half performance sees Tite's men victorious
Serbia made life difficult for Brazil in their Group G opener, but Tite's side finally found a way through with the help of Richarlison's double, making it nine in his last seven for his national team in all competitions.
The forward's goals were his 18th and 19th in the famous yellow shirt. Since his debut in September 2018, no other player has scored more often for Brazil than Richarlison.
Serbia managed to keep Brazil out for over an hour with a resilient defensive rearguard, but they desperately lacked an attacking threat as they became the fourth team at the 2022 World Cup to not register a shot on target in their first match.
Serbia have now lost eight of their 10 World Cup matches since becoming an independent nation, the highest loss percentage (80 per cent) of any country with over 10 games at the tournament.
Thiago Silva became the oldest player to play for Brazil at a World Cup match at 38 years and 63 days, and his experience helped the Selecao to make it 20 opening games at the World Cup unbeaten, a run stretching all the way back to 1938.