In the opening match of Group C in Lusail, a brave and shrewd Saudi Arabia team rallied from behind to stun the two-time world champions Argentina, causing one of the biggest upsets in World Cup history.
While Argentina had three goals disallowed for offside, and the 51st-ranked Saudi Arabia could have been defeated by halftime, Lionel Messi opened the scoring from the penalty spot.
Saleh Al-Shehri's low effort equalised the score for Saudi Arabia 10 minutes after halftime, and Salem Al Dawsari sent them in front to agitate the crowd.
The Green Falcons played tough defence and ruthless offence to deny Argentina's potent front line the opportunity to win their fourth World Cup. This triumph made the group much more open.
Argentina, coached by Lionel Scaloni, entered as one of the favourites after going undefeated in their previous 36 games (including a win at the 2021 Copa America).
Now, everything rests on their shoulders as they try to win their first World Cup since 1986 and send Messi off with a bang in what is likely his final tournament appearance.
On Saturday, they will play Mexico, while Saudi Arabia will take on Poland.