Doha (AFP) -
Saudi Arabia pulled off one of the greatest upsets in World Cup history on Tuesday, roaring back to beat Argentina 2-1 -- a result described by Lionel Messi as a 'heavy blow'.
Copa America champions Argentina came into the match in Qatar on a 36-match unbeaten streak and appeared to be on their way to a straightforward victory after Messi stroked home an early penalty.
Lionel Scaloni's team could have put the game beyond Saudi Arabia's reach in the first half but had three goals chalked off for offside.
Saudi Arabia, ranked a lowly 51st in the world, equalised early in the second half through Saleh Al-Shehri, silencing the hordes of Argentina fans.
And just minutes later the Green Falcons were in front when Salem Al-Dawsari rifled an unstoppable shot into the top corner after a delightful piece of trickery.
Argentina laid siege to the Saudi goal as the minutes ticked down but goalkeeper Mohammed Al-Owais proved unbeatable and the final whistle sparked scenes of jubilation.
Argentina, who last failed to reach the knockout phase in 2002, will be dumped out as early as Saturday if they lose their second match to Mexico.
'It's a very heavy blow, a defeat that hurts, but we must continue to have confidence in ourselves,' said Messi, who has never won the World Cup in his illustrious career.
'This group is not going to give up. We will try to beat Mexico.'
Saudi's French coach Herve Renard said the 'stars were aligned' for his team.
'We made history for football,' he added. 'It will stay forever, this is most important. But we also have to think about looking forward. We still have two difficult games before us.'
- Misfiring Lewandowski -
Defeat is a bitter setback for Argentina, who were one game away from equalling Italy's all-time record of 37 matches unbeaten.
Scaloni insisted his team had not taken their opponents lightly.
'What comes ahead is to rise up, to face Mexico,' he said. 'They will be tough, as everyone is at the World Cup. Now we need to win two games to move on.
'Of course this is difficult, but regardless of the result today, we would anyway try to win all the games.'
Poland played out a goalless draw with Mexico in the other Group C match, with Robert Lewandowski missing a second-half penalty.
The Barcelona striker was denied a maiden World Cup goal when his 58th-minute spot-kick was saved by veteran goalkeeper Guillermo Ochoa.
In the last match of Tuesday, Messi's Paris Saint-Germain team-mate Kylian Mbappe will be licking his lips when France face an Australia side desperately lacking star power in Group D.
France coach Didier Deschamps is without first-choice midfielders Paul Pogba and N'Golo Kante for the whole tournament while Ballon d'Or winner Karim Benzema has also been ruled out.
Mbappe will lead a French attack in which veteran Olivier Giroud replaces Benzema.
Denmark drew 0-0 with Tunisia in the other match in the group, with talisman Christian Eriksen appearing in his first match in a major tournament since suffering a cardiac arrest during the European Championship last year.
- Ronaldo's Manchester exit -
Saudi Arabia's dramatic win shifted the focus -- for a time, at least -- to the action on the pitch, but Messi's great rival Cristiano Ronaldo was soon making the headlines again.
Manchester United said that the 37-year-old forward, currently with the Portugal squad in Qatar, will leave the club with 'immediate effect' following last week's incendiary television interview.
Ronaldo had said he felt 'betrayed' by the club and had no respect for manager Erik ten Hag.
And in Qatar, Belgium's Jan Vertonghen said he was 'afraid' to talk about human rights after European nations decided not to wear a rainbow-themed captain's armband.
Seven countries, including England and Germany, abandoned plans to wear the armbands at the World Cup because of the threat of FIFA disciplinary action, including bookings.
They had been viewed as a symbolic protest against laws in the host nation, where homosexuality is illegal.
'I'm afraid if I say something about this I might not be able to play tomorrow,' the defender said.
'It's an experience I've never felt in football before. I feel controlled. I'm afraid to even say something about this.'