FIFA World Cup 2022 favourites Argentina suffered a shock 2-1 loss to minnows Saudi Arabia following their 2-1 loss on Tuesday.
Messi arrived in Qatar for a fifth attempt at finally winning football's biggest prize.
But it got off to a nightmarish start despite Messi scoring the opening goal in the 10 minute from a penalty spot in a dominant first half display.
Saudi Arabia, the second-lowest ranked team in the tournament after Ghana, put up a fighting display in the second half.
Saleh Al-Shehri and Salem Al-Dawsari goal left Argentina and Messi looking utterly shell-shocked in the Group C opener.
Meanwhile, Argentina arrived in Qatar on a 36-match unbeaten streak, one shy of tying Italy's record in international men's soccer, set from 2018-21.
Argentina has not lost since falling to Brazil 2-0 in the 2019 Copa América. Argentina first won the World Cup in 1978, and then again in 1986 - one year before Messi was born.
The team reached the final in 2014 and lost to Germany, and in a bitter follow-up four years later was eliminated in the round of 16 in Russia.
Messi, meanwhile, is one of four players making their fifth World Cup appearance. He joins Portugal forward Cristiano Ronaldo, and Mexico teammates Guillermo Ochoa and Andrés Guardado.
Fans took to social media to post their reactions.
Here are a few reactions.
