Yan Liming, who works with a Chinese telecom firm, said he was there to watch India's volleyball match.
Al-Nassr won their first ever Arab Club Champions Cup title with in a 2-1 extra-time win over fellow Saudi side Al-Hilal.
It was a historic night for Ronaldo who became the first player to make 200 international appearances.
Benzema, who ended a trophy-laden 14 years at Real this week, joins Al-Ittihad on a three-year deal and will wear the No. 9 shirt.
The 38-year-old, who missed the final matchday due to injury, said the league was very competitive but that there were many opportunities to grow.
Al-Nassr failed to win any titles this season and finished the league in second place, five points behind champions Al-Ittihad.
The offer from the Saudi club is the only one Messi has received so far, the source added.
Ronaldo, who joined the Saudi soccer club on a deal until 2025 after leaving Manchester United last year, earned $136 million with Forbes saying his annual playing salary went up to an estimated $75 million.
Brazilian Talisca also hit the net twice in the 5-0 victory over Al-Adalah on Tuesday and is the league's joint top-scorer with 16 goals.
Cristiano Ronaldo set a new record for the most international caps as Portugal played Liechtenstein on Thursday.