Saudi giants Al Ittihad take on city rivals Al Ahli in the AFC Champions League semi-finals Monday as one of Asia's oldest and fiercest local derbies stages arguably its most important edition yet.
Having fought on the domestic stage for three-quarters of a century, the stakes are unprecedented for the Jeddah teams with the winner over two legs reaching a final against Uzbekistan's Bunyodkor or South Korea's Ulsan Hyundai.
The two clubs are among the most venerable in Asia -- Al Ittihad were formed in 1929, and Al Ahli eight years later -- and they have been frequent foes in Saudi Arabia's league and cup competitions since their first clash in 1938.
It is not the first time that two clubs from the same country have been drawn together in the last four: South Korea's Jeonbuk Motors and Ulsan Hyundai met in 2006, and Japan's Gamba Osaka and Urawa Reds clashed in 2008.
But none of those other teams shared an age-old rivalry like Al Ittihad and Al Ahli have developed over the years.
Al Ittihad, who are the nominal home side for the first leg at the shared Prince Abdullah Al Faisal Stadium, have the richer history with AFC Champions League wins in 2004 and 2005, plus eight domestic league titles.
By contrast, Al Ahli have only two league titles to their name, but they have held the edge in recent times after they beat Al Ittihad to win the King's Cup in 2011 and finished second in the league behind Al Shabab earlier this year.
Signup to our newsletter and follow us on Facebook and Twitter!
Al Ittihad were fifth, their worst league performance in 14 years, but their form has picked up dramatically since the appointment of Raul Caneda as head coach in February.
Under the Spaniard, Al Ittihad were unbeaten in 22 games in all competitions until this month's 2-1 away loss to Guangzhou Evergrande in the second leg of the Asian quarter-finals -- although they still advanced 5-4 on aggregate.
The Tigers will have to cope with the absence of veteran defender Redha Takar, who picked up yellow cards in each of the quarter-final games.
While there will be little travel involved in the semi-final, whose first leg was brought forward two days because of Eid celebrations in Saudi Arabia, the winner faces a trip to either Uzbekistan or South Korea for next month's final.
Bunyodkor emerged from a hard-fought quarter-final against Australia's Adelaide United, which went to extra-time before they eventually prevailed 5-4 on aggregate.
Formed only in 2005, the four-time Uzbek champions are keen to add the continental title to their trophy haul after going out in the semi-finals in 2008 and the quarter-finals a year later.
The team coached by Uzbek legend Mirdjalal Kasimov have done well this year against Korean clubs in the AFC Champions League, beating Pohang Steelers twice in the group stage and eliminating Seongnam Ilhwa Chunma in the round of 16.
But Ulsan are unbeaten in this year's competition and Kim Ho-Gon's side impressed in their quarter-final against Al Hilal as they hammered the Saudi club 4-0 in the second leg to reach the last four for the first time since 2006.
K-League clubs have traditionally done well in the AFC Champions League and Ulsan will be looking to become the fourth consecutive Korean side to appear in the final.
Bunyodkor will be without midfielder Anvar Gafurov, who was sent off in the second leg of the quarter-final against Adelaide.