Ronaldo, the Al Nassr captain, was reportedly rested for the opening knockout match of the rebranded competition.

Now 40, the Portuguese forward played in his team's shock domestic defeat to Al Orobah last Friday and was left in Riyadh for the resumption of the continental competition.

In Ronaldo's absence, winter signing Jhon Duran had a night to forget at the Azadi Stadium.

A high-profile recruit in January from Premier League club Aston Villa, the Colombian could not add to the two goals he scored on his tournament debut last month.

Duran went close twice midway through the first half.

On 20 minutes, he ran in behind the Esteghlal defence but shot straight at goalkeeper Hossein Hosseini. Ayman Yahya latched onto the rebound but his effort was blocked on the goal line.

Duran should have opened the scoring six minutes later after he was teed up by former Chelsea winger Angelo Gabriel, but his tame effort was saved by Hosseini.

Al Nassr, who dominated possession in the first half, looked set to break the deadlock just before the hour.

Former Inter Milan midfielder Marcelo Brozovic released Duran with a ball over the hosts' backline, only for the forward to fail to get enough purchase on his attempted lob to beat Hosseini.

In the 69th minute and with Hosseini stranded, Duran struck the base of the Esteghlal post from a tight angle.

Minutes later, he shot high and wide from the left-hand side of the area.

Al Nassr will host Esteghlal, whom they beat in the group stages, in the second leg in Riyadh in seven days' time.

The Saudi side's manager Stefano Pioli will hope to welcome back Ronaldo to his starting lineup.

Ronaldo has six goals in five Champions League Elite appearances this season.

In the night's other last-16 match, UAE champions Al Wasl were held 1-1 at home in the first leg of their tie with two-time Asian champions Al Sadd of Qatar.

Al Wasl made the perfect start at Zabeel Stadium on three minutes, when captain Ali Saleh put his side ahead with a brilliant cut-back and finish.

Al Sadd levelled with 22 minutes remaining.

Akram Afif, the reigning Asian Player of the Year, whipped in a cross from the left for Abdullah Al Yazidi to head home. The second leg takes place in Al Rayyan next Monday.