Indonesia coach Alfred Riedl hopes that his inside knowledge of opponents Vietnam will give his side an edge as they look to advance to their first AFF Suzuki Cup final in six years.
The two nations face off over two legs in the semifinals, starting at Bogor, near Jakarta on Saturday.
Riedl was Vietnamese national boss over three spells, most recently in 2007. He says the Golden Stars are one of the top two teams in the region.
"In my opinion they are the second best team in Southeast Asia behind Thailand," Riedl told the tournament's official website.
"They are an experienced team with talented players. Their coach [Nguyen Huu Thang], who is my former captain of the national team, is doing a good job there.
"It will be very difficult for us to advance to the final. They might be a little bit better than us, but they will have to prove it."
Indonesia have faced Saturday's opponents twice in the last couple of months, with the Garuda playing out a 2-2 draw in Yogyakarta in October before losing 3-2 in Hanoi three last month.
With two of his centre-backs serving suspensions for this game, he'd be concerned about the defensive frailties of a side who conceded seven goals in three Group A matches.
After netting twice so far in the 2016 Suzuki Cup, Vietnam's Le Cong Vinh is now just three goals away from becoming the tournament's all-time leading scorer.
"I've known him personally for 13 years," Riedl said. "He's a great guy and a good player.
"We've tried in our training to do some exercise because we know his movement. It will be difficult to stop him, but we are prepared for this.
"But he is not alone, the other players are good also."
Vietnam won their one and only AFF title in 2008.