Harry Kewell and Hernan Crespo, who once opposed each other in a UEFA Champions League final, will square up again in the Asian equivalent on Saturday.

Australian great Kewell is now in charge at Japan's Yokohama F-Marinos who will host the United Arab Emirates' Al Ain, coached by former Argentina striker Crespo, in the first leg of the AFC Champions League final.

Kewell was part of Liverpool's UEFA Champions League-winning side in Istanbul in 2005, when the Anfield Club found themselves 3-0 down at half-time to AC Milan, with Crespo scoring two of the goals, before famously coming back to draw 3-3 and win on penalties.

Crespo was a fan favourite at Chelsea, helping them to win the English Premier League in 2005-6 under Jose Mourinho, when Kewell's Liverpool came third.

Al Ain are the UAE's most successful club and will be playing in the final for the fourth time, having won it in 2002 and reached the final in 2005 and 2016.

Yokohama are attempting to become the fourth Japanese side to win the trophy after three-time winners Urawa Red Diamonds, Gamba Osaka and Kashima Antlers.

Kewell, who also played in the 2007 Champions League final and an FA Cup final for Liverpool, said the two-legged decider would be a whole new ball game.

"Finals are usually a one-off game and that's why I've always said two-legged semi-finals are always the toughest games," Kewell said.  

"When you get to a final you should enjoy it. But this (home-and-away final) is something new for me as well.

"You're going to have to be able to control your emotions," he added.

"You're not going to be out of it from the first game. You're always going to have a second chance. 

"Whatever happens on May 11 is not going to determine everything."

Crespo has guided Al Ain to the final against the odds, eliminating Cristiano Ronaldo's Saudi side Al Nassr in the quarter-final on penalties.

They then ended Al Hilal's record streak of 34 consecutive wins in the semi-final.

Goalkeeper Khalid Eisa was in the Al Ain side beaten by South Korea's Jeonbuk in the 2016 final and is grateful for a second chance under Crespo.

"I had a bad period before (this year's Asian Cup)," Eisa admitted. 

"I am glad to be playing well again, especially as we are now at the important stage of the season and I thank the confidence of the coach and the club management in me."

The second leg will take place in Al Ain on May 25.