Socceroos defender Chris Herd has been ruled out of the Asian Cup with an Achilles injury, Football Australia said on Thursday.

The 25-year-old Aston Villa player underwent scans after reporting pain before the hosts thumped Oman 4-0 on Tuesday to advance to the quarter-finals.

"It's disappointing for the team and especially for Chris that he is unable to continue in the tournament," head coach Ange Postecoglou said in a statement.

"It has been determined it is in Chris's best interests that he returns to Aston Villa for rehabilitation to ensure he can get back on the pitch."

Postecolgou will be hoping Ivan Franjic can get through the Asian Cup without injury, as Herd is the only other recognised right-back in the Australian squad.

According to tournament rules, Herd cannot be replaced in the squad, meaning the Socceroos will have to continue through the tournament with a roster of 22 players instead of 23.

Undefeated Australia will top Group A if they draw with or beat South Korea in Brisbane on Saturday and they may have to do so without skipper Mile Jedinak, who is uncertain of when he will return after twisting his ankle in the 4-1 win over Kuwait.

Reuters