Roberto Mancini's Saudi Arabia fought back to defeat Oman 2-1 in the dying seconds at the Asian Cup on Tuesday, but only after some VAR confusion.
Also in Group F, Thailand beat Kyrgyzstan 2-0 with Supachai Chaided scoring both goals.
The ambitious Saudis beat eventual champions Argentina in the group phase of the 2022 World Cup and returned to Qatar as one of the favourites for the regional tournament.
They are seeking a record-equalling fourth Asian Cup, off the back of a big-money recruitment drive that has lured the likes of Neymar and Cristiano Ronaldo to the kingdom's domestic league.
Saudi Arabia is also set to host the 2034 World Cup.
Their opening match at the Asian Cup started badly when they conceded a penalty -- and finished in farcical scenes in front of a bemused crowd of 41,987.
Deep into injury time and with the Saudis pushing to make it 2-1, Ali Al-Bulayhi headed in following a corner to spark pandemonium for what they thought was the winner.
The goal was disallowed for offside by the assistant referee, and was checked by VAR. He appeared in replays to have been onside.
Then came the confusion when it appeared that referee Shaun Evans had stuck with the original offside call and the game restarted, only for him to call back play and award the goal.
Bulayhi, who celebrated by inflating a green balloon as his teammates mobbed him, afterwards called his winner "a gift to the Saudi people".
"Scoring at the end of the match, this is what great players do," said the 34-year-old defender.
Mancini, who took the Saudi reins in September, said his side made mistakes in the first half "but this is normal in the first game".
His opposite number Branko Ivankovic said the "Saudi team deserved the victory", citing the tiredness of his players as a reason behind Oman's late collapse.
- Jeers to cheers -
Mancini's men went behind in the 14th minute when Evans gave a penalty for a trip on Oman forward Muhsen Al-Ghassani, having checked the VAR screen.
Salaah Al-Yahyaei converted to give lower-ranked Oman a surprise lead.
Oman sat back for the remainder of the first half, but Saudi Arabia failed to apply any serious pressure.
After the break the Saudis continued to huff and puff, but had only registered two shots on target by the hour mark.
As the clock ticked down and jeers began to ring out from the Saudi fans, the men in green needed a moment of magic.
And that was what they got, substitute Abdulrahman Ghareeb -- only on the pitch three minutes -- jinking his way through the Omani back line before stroking in the equaliser with 12 minutes left.
The Saudis then pushed for the winner, leading to Bulayhi's dramatic late intervention.
Earlier, Buriram United striker Supachai prodded in from close range on 26 minutes to give Thailand the lead over Kyrgyzstan.
He got his second in similar style just after the break when the ball again fell his way with the goal gaping.
Reigning champions Qatar return to action on Wednesday when they will look to seal their place in the last 16 with victory over Tajikistan.
In the other game in Group A, China play Lebanon.