Defending champions and hosts Qatar became the first team to book their place in the Asian Cup last 16 with a 1-0 win over debutants 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 Akram Afif, who scored twice in Qatar's opening 3-0 victory over Lebanon, hit the winner early in the first half in front of 55,000 with another clinical finish.

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 returning to the tent-like Al Bayt Stadium, where they lost 2-0 to Ecuador in the opening game of the World Cup just over a year ago.

The 2019 Asian champions gave another solid performance, illuminated by a flash of brilliance from Afif.

The forward raced onto a through ball from Almoez Ali in the 17th minute before stabbing it deftly past goalkeeper Rustam Yatimov.

Coach Tintin Marquez -- only in the job since early December -- 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 in the blink of an eye when Afif opened the scoring, but Qatar should have had more after dominating the rest of the first half.

Tajikistan had a close shave when Manuchekhr Safarov appeared to take a swipe at Ali in the box midway through the first half, only for a VAR check to rule out a penalty for Qatar.

The Central Asians escaped again when Zoir Dzhuraboev cleared off the line from Ali after a goalkeeping blunder from Yatimov shortly before half-time.

Tajikistan had a chance early in the second half when Alisher Dzhalilov prodded the ball past the onrushing Barsham, but the striker could not catch up in time to steer it into the net.

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.

They still have a chance to qualify for the knockout round and face Lebanon on Monday.

Qatar play China in their final group match the same day.