Cristiano Ronaldo's Al Nassr travel to Iran in the Asian Champions League next week with his side one of three from Saudi Arabia in the last 16 of the region's top club competition.
Saudi teams dominated the tournament's West zone league stage, with four-time Asian champions Al Hilal leading Al Ahli and Al Nassr in the top three in the final table.
Saudi Arabia has shaken up football by spending heavily on stars from Europe, starting with Ronaldo's move in late 2022, and the desert nation will host the World Cup in 2034.
Al Hilal, the last side from Saudi Arabia to win the Champions League, in 2021, topped the league stage on goal difference from Al Ahli with both unbeaten in eight matches.
Al Nassr finished five points clear of fourth-placed Al Sadd of Qatar and Ronaldo's side take on Iran's Esteghlal over two legs, the first in Tehran on Monday.
Former Real Madrid and Manchester United star Ronaldo scored six goals in the league stage and is still going strong at the age of 40.
A first Asian crown would add to a bulging trophy haul that already includes five Uefa Champions League titles.
The Portuguese has been joined at Al Nassr by Colombian striker Jhon Duran, although the big-money signing from Aston Villa was sent off during a Saudi league game last week.
The red card infuriated Ronaldo, who lashed out at the referee and booted the ball into the stands before continuing to remonstrate with the officials.
Coach Stefano Pioli will need his players to keep their heads against Esteghlal, who Al Nassr beat 1-0 in the league stage thanks to a late goal from former Manchester City defender Aymeric Laporte.
"We must try to improve every day as we have not yet reached the level where we can compare ourselves with the first level of world football," Pioli said.
Al Hilal can no longer call on the services of Brazil's Neymar but they will still start as heavy favourites in their last-16 tie against Uzbekistan's Pakhtakor.
Al Ahli meanwhile saw their front three of England's Ivan Toney, Brazil's Roberto Firmino and Algeria's Riyad Mahrez all enjoy goalscoring form in the league stage.
German coach Matthias Jaissle will need them keep it going in the last 16 against Qatar's Al Rayyan.
"We achieved a historic record in this edition without losing, and this is not easy," he said.
"We have the support of the fans and we look forward to winning this tournament."
JAPANESE CLUBS LEAD EAST
Japanese sides led the way in the East zone's league phase, with last season's runners-up Yokohama F-Marinos topping the table ahead of compatriots Kawasaki Frontale.
Yokohama, now coached by Gareth Southgate's former England assistant Steve Holland, play China's Shanghai Port in the last 16.
Kawasaki face Shanghai Shenhua while a third Japanese team, the domestic champions Vissel Kobe, take on South Korea's Gwangju.
At least one non-Japanese team is guaranteed to advance in the East zone, with Malaysia's Johor Darul Ta'zim meeting Thailand's Buriram United.
Johor's Argentine coach Hector Bidoglio has been impressed with his team's performances so far.
"Before the start of the competition we set our target to qualify for the next stage," he said after they booked their place with a 5-2 win over South Korea's Pohang Steelers.
"But now we have not only qualified but we did it by showing our type of football."
Last-16 games are played over two legs, with the winners going through to a finals stage to be played in Saudi Arabia in April and May.