Al Khor, Qatar: Akram Afif struck again as holders and hosts Qatar became the first team into the Asian Cup last 16 with a 1-0 win over Tajikistan on Wednesday.
China's 0-0 draw with Lebanon earlier in the day means Qatar are guaranteed to go through to the knockout round as Group A winners.
Livewire forward Afif, who scored twice in Qatar's opening 3-0 victory over Lebanon, hit the winner midway through the first half in front of 55,000 at the tent-like Al Bayt Stadium.
"I'm very pleased to qualify after two matches," said Qatar coach Tintin Marquez, who has only been in the job since early December after replacing Carlos Queiroz.
"It was a difficult game but we always knew it would be. We played against a tough, strong team, but we didn't give them the chance to score."
Asian Cup debutants Tajikistan finished with 10 men after Amadoni Kamolov was sent off for kicking out at Ahmed Al-Ganehi's face late in the game, the first dismissal of the tournament.
Qatar were beaten 2-0 by Ecuador in the opening game of the World Cup just over a year ago at Al Bayt and went on to lose all three group matches, the worst record of any World Cup host.
The 2019 Asian champions are out to banish those memories and Afif especially appears on a mission.
The forward raced onto a through ball from Almoez Ali in the 17th minute before stabbing it deftly past goalkeeper Rustam Yatimov for another clinical finish.
"Almoez is one of my best friends and we understand each other very well," Afif said of his partnership with Ali, who scored a record nine goals as Qatar won the title for the first time in 2019.
"We have been playing together for a long time so we understand what each other is going to do just with a look.
"We hope the best is still yet to come."
Marquez made five changes to the starting lineup that faced Lebanon, dropping captain Hassan Al-Haydos to the bench.
Tajikistan made a positive start and Rustam Soirov stung Qatar goalkeeper Meshaal Barsham's hands with an early shot from inside the box.
All that changed when Afif opened the scoring and Qatar should have had more after dominating the rest of the first half.
"Every match is difficult and you are talking about the Asian Cup," said Marquez.
"The opposition started with high pressure but we were able to handle that.
"We had a problem with possession at the start but we controlled the match and achieved what we wanted to achieve."
Kamolov was sent off in the 81st minute when he lashed out with his boot at Ganehi when going down under a challenge.
Tajikistan drew 0-0 with China in their opening game for their first point ever at the Asian Cup and still have a chance to qualify for the knockout round.
Coach Petar Segrt knows that their final group game against Lebanon on Monday is "all or nothing."
"Everybody makes compliments to me, you can give compliments to Tajikistan, but at the end, the result is important," he said.
Qatar play China in their final group match the same day.